Tiếng Anh B4 (Dành cho sinh viên khoa hoá học) Tác giả: Nguyễn Tất Thắng Trường Đại học Đà Lạt, 2009

8/13/2019 Tiếng Anh B4 (Dành cho sinh viên khoa hoá học) Tác giả: Nguyễn Tất Thắng Trường Đại học Đà Lạt, 2009

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TRÖÔØNG ÑAÏI HOÏC ÑAØ LAÏT

GIAÙO TRÌNH

TIEÁNG ANH B4(Daønh cho Sinh vieân Khoa Hoaù Hoïc)

NGUYEÃN TAÁT THAÉNG

2002



Tieáng Anh B4 (Daønh cho Sinh vieân Khoa Hoaù Hoïc - 2 -

Nguyeãn Taát Thaéng Khoa Ngoaïi Ngöõõ

MUÏC LUÏCMUÏC LUÏC.................................................................................................................................... 1

ÑEÀ CÖÔNG CHI TIEÁT HOÏC PHAÀN............................................................................................ 4 Unit One: INTRODUCTION TO CHEMISTRY.......................................................................... 8

I. Vocabulary in context: Put the words / phrases into the blanks ............................................ 9

II. Comprehension question: .................................................................................................... 9

III. Vocabulary in new context: Put the words / phrases into the blanks .................................. 9

IV. Grammar review: ............................................................................................................. 11

Unit Two: ATOMS..................................................................................................................... 16

I. Vocabulary in context: ........................................................................................................ 16

II. Vocabulary in new context: ............................................................................................... 17

III. Comprehension questions: Write T if the following statement is true, and F if false....... 17

IV. Grammar: PASSIVE VOICE STRUCTURE .................................................................... 18 Unit Three: STRUCTURE OF AN ATOM................................................................................. 26

I. Vocabulary in context ......................................................................................................... 27

II. Match words or phrases in column A and column B.......................................................... 27

III. Answer the questions........................................................................................................ 28

IV. Structure: Passive (continued).......................................................................................... 28

Unit Four: PROPERTIES OF ATOMS....................................................................................... 32


II. Comprehension questions.................................................................................................. 33

III. Grammar .......................................................................................................................... 34

VI- Writing:............................................................................................................................ 36

Unit five: ELEMENTS AND SYMBOLS OF ELEMENTS ....................................................... 39


II. Vocabulary in new context ................................................................................................ 40

III. Comprehension questions................................................................................................. 41

IV. Grammar: Relative Clauses (review)............................................................................... 41

Unit Six : MOLECULES............................................................................................................ 49

I. Vocabulary in Context ........................................................................................................ 49


III. Grammar .......................................................................................................................... 50

Unit Seven: THE VARIETY OF MOLECULES........................................................................ 55

I. Vocabulary in context ......................................................................................................... 56 II. Comprehension questions.................................................................................................. 56

III. Grammar .......................................................................................................................... 57

Unit Eight: GASES, LIQUIDS AND SOLIDS............................................................................ 63



III. Grammar: Verb + ing Structure........................................................................................ 66

Unit Nine: A COMPOUND'S IDENTITY.................................................................................. 72







III. Review on vocabulary:..................................................................................................... 75

IV. Grammar – Preposition .................................................................................................... 75

Unit Ten: IONIC AND COVALENT BONDS ........................................................................... 79


II. Vocabulary in new context: ............................................................................................... 80

III. Comprehension Question ................................................................................................. 81

Unit Eleven: CHEMICAL REACTIONS ................................................................................... 94


II. Vocabulary in new context ................................................................................................ 95

III. Reading comprehension................................................................................................... 96

Unit Twelve: OXIDATION AND REDUCTION..................................................................... 101

I. Vocabulary in context ....................................................................................................... 101

II. Comprehension questions................................................................................................ 102

III. Grammar review ............................................................................................................ 102 Unit Thirteen COMPOUNDS................................................................................................... 106

I. Vocabulary........................................................................................................................ 107


III. Review on Vocabulary:.................................................................................................. 109

IV. Review on Grammar: ..................................................................................................... 110

Unit Fourteen: MIXTURES ..................................................................................................... 112

I. Vocabulary........................................................................................................................ 113


III. Grammar review ............................................................................................................ 114

GLOSSARY............................................................................................................................. 120 REFERENCES:........................................................................................................................ 128





ÑEÀ CÖÔNG CHI TIEÁT HOÏC PHAÀNMoân Tieáng Anh B 4 – Tieáng Anh chuyeân nghaønh

daønh cho Sinh vieân Khoa Hoùa Hoïc

1. Teân hoïc phaàn: Tieáng Anh B4

2. Soá ñôn vò hoïc trình: 5 – Toång coäng: 75 tieát/hoïc kyø.

3. Trình ñoä: Sinh vieân khoâng chuyeân Ngoaïi ngöõ (ngaønh Hoùa Hoïc) naêm thöù hai (hoïc kyø IV)

4. Phaân boá thôøi gian: 6 tieát/ tuaàn.

5. Ñieàu kieän tieân quyeát:

Sinh vieân phaûi thi ñaït caùc hoïc phaàn tröôùc goàm Tieáng Anh B1, Tieáng Anh B2 vaø Tieáng

Anh B3 môùi ñöôïc hoïc tieáp moân Tieáng Anh B4 cuûa hoïc kyø II naêm thöù 2.

6. Toùm taét noäi dung hoïc phaàn:

Tieáng Anh B4 daønh cho sinh vieân khoâng chuyeân ngöõ ngaønh Hoùa Hoïc laø hoïc phaànñöôïc khoa Ngoaïi ngöõ aùp duïng ñaàu tieân vaøo naêm hoïc 2001-2002 vaø ñöôïc chænh lyù boåsung vaø hoaøn thieän cho sinh vieân ngaønh Hoaù Hoïc. Sinh vieân ñaõ hoïc qua Tieáng Anh B1,B2, B3 vaø ñaõ ñöôïc laøm quen vôùi caùc kieán thöùc cô baûn veà tieáng Anh. Tieáng Anh B4 chuûyeáu reøn kyõ naêng ñoïc hieåu ñoái vôùi caùc baøi ñoïc mang tính chaát chuyeân ngaønh ñoái vôùingaønh maø sinh vieân ñang theo hoïc. Tieáng Anh B4 cho sinh vieân ngaønh Hoùa bao goàm 14

baøi ñoïc ñöôïc choïn loïc töø caùc taøi lieäu chuyeân moân, giôùi thieäu caùc khaùi nieäm cô baûn veà vaätlyù, keøm caùc caâu hoûi ñoïc hieåu vaø moät soá baøi taäp cuûng coá ngöõ phaùp.7. Nhieäm vuï cuûa sinh vieân:

- Tham gia ñaày ñuû caùc buoåi hoïc, vaéng phaûi coù pheùp. Sinh vieân naøo vaéng khoâng pheùp quaù 4

buoåi seõ khoâng ñöôïc döï thi.

- Chuaån bò baøi tröôùc khi ñeán lôùp.

- Chuaån bò ñaày ñuû phaán, khaên lau baûng cho giaùo vieân vaø caùc thieát bò khaùc (neáu caàn)

- Tham gia thi giöõa kyø vaø thi hoïc kyø.

8. Taøi lieäu hoïc taäp:

- Giaùo trình chính: The World Book of SCIENCE POWER – Version No 1 – Chemistry,

Physics, and Life Sciences, vaø caùc taøi lieäu ñöôïc caäp nhaät treân maïng Internet töø caùc trang

coù uy tín vaø ñöôïc doäc giaû tin caäy.

9. Tieâu chuaån ñaùnh giaù sinh vieân:





Sinh vieân ñöôïc ñaùnh giaù döïa treân nhöõng tieâu chuaån sau.

- Dö lôùp vaø phaùt bieåu. - Thi giöõa kyø. - Thi hoïc kyø

10. Thang ñieåm: 100% quy thaønh 10

- Döï lôùp vaø phaùt bieåu: 10% - Thi giöõa kyø: 30% - Thi cuoái kyø: 60%

11. Muïc tieâu cuûa hoïc phaàn:

Hoïc phaàn Tieá ng Anh B4 laø hoïc phaàn tieá ng Anh chuyeân ngaønh daønh cho sinh vieân khoâng chuyeân

ngöõ naêm thöù hai hoïc kyø II sau khi ñaõ hoaøn thaønh caùc hoïc phaàn cô baûn cuøng vôùi caùc kyõ naêng thöïc

haønh tieáng cô baûn. Muïc tieâu cuûahoïïc phaàn Tieáng Anh B4 chuyeân ngaønh Vaät lyù laø nhaèm:

- Giôùi thieäu nhöõng khaùi nieäm cô baûn veà hoùa hoïc baèng tieáng Anh, nhö nguyeân töû , phaân töû,

hôïpp chaát, v.v.

- Cung caáp cho sinh vieân moät khoái löôïng töø vöïng chuyeân ngaønh: thuaät ngöõ, khaùi nieäm…

- Naâng cao kyõ naêng ñoïc hieåu qua caùc baøi ñoïc mang tính chuyeân moân hôn laø caùc baøi ñoïc

mang tính chaát kieán thöùc phoå thoâng nhö caùc hoïc phaàn tröôùc.

- Cuûng coá kieán thöùc ngöõ phaùp qua caùc baøi taäp coù lieân quan ñeán noäi duïng cuûa baøi hoïc.

12. Noäi dung chi tieát hoïc phaàn:

Moân Tieáng Anh B4 ñöôïc hoïc trong 12,5 tuaàn.

TUAÀN

THÖÙ BAØI Noäi Dung Baøi Hoïc

1

Baøi 1

Introduction To Chemistry

Giôùi thieäu veà Hoaù hoïc: caùc thuaät ngöõ cuûa

caùc ngaønh chính trong nghaønh Hoùa

Ngöõ Phaùp: OÂn taäp caùc thì cô baûn trong

tieáng Anh

2

vaø

3

Baøi 2

Atoms

Baøi 3:

Structure Of An Atom

Baøi 4:

Properties Of Atoms

Caùc thuaät ngöõ veà nguyeân töû, caáu truùc

nguyeân töû vaø tính vhaát cuûa nguyeân töû

Ngöõ Phaùp: Theå thuï ñoäng, caùc loaïi caâu caên

baûn nhö caâu ñôn, caâu gheùp vaø caâu phöùc





4

Bai( 5:

Elements And Symbols Of

Elements

Nguyeân toá vaø caùc kyù hieäu nguyeân toá

Ngöõ Phaùp: Caâu lieân heä





5

Baøi 6:

Molecules

Baøi 7:

The Variety Of Molecules

Phaân töû, Söï ña daïng cuûa phaân töû

Ngöõ Phaùp:+Caáu truùc song song (both…and, etc)

+ Caùc cuïm töø due to,because of, v.v.

6 OÂn taäp OÂn thi giöõa kyø

7 Baøi 8:

Gases, Liquids And Solids

Ga, Chaát loûng vaø chaát raén

Ngöõ phaùp: Gerund

8 Baøi 9

A Compound's Identity

Baøi 10

Ionic And Covalent Bonds

Ñaëc tính cuûa Hôïp chaátLieân keát ion vaø lieân keát hoùa trò

Ngöõ phaùp: Giôùi töø

9 Baøi 11

Chemical Reactions

Baøi 12:Oxidation And Reduction

Phaûn öùng hoùa hoïc

OÂ xy hoùa khöû

OÂn taäp ngöõ phaùp

10 Baøi 13

Compounds

Hôïp chaát

OÂn taäp töø vöïng

11 Baøi 14:

Mixtures

Hoãn hôïp

OÂn taäp ngöõ phaùp vaø töø vöïng

12 vaø 13 OÂn taäp OÂn thi cuoái kyø





UNIT ONE: INTRODUCTION TO CHEMISTRYChemistry is the scientific study of the substances that make up the universe.

Chemists investigate the properties of substances and how different conditions

affect the way substances behave. All things – from rock to skin to air – consist of

different combinations of chemical elements. Elements are made up units called

atoms, which are so tiny that billions of them make up the smallest speck. When

atoms combine, they usually form units called molecules, which are the building

blocks of most chemical compounds. An understanding of elementary particles –

atoms and molecules – form the basic of chemistry.

Chemistry seeks the answers to two questions: (1) Of what is matter composed?

(2) How are its transformations from one form into another related to its

composition? The enormous material benefits to all of us, which men customarilyassociate with the word chemistry, are largely by-products of the attempt to answer

these two questions about the nature of matter.

Even that branch of science called chemistry is too vast to be thoroughly

mastered by anyone. Therefore, as a matter of convenience, its content is further

subdivided. The branches of chemistry are: (1) Theoretical Chemistry, (2) Inorganic

Chemistry, (3) Analytical Chemistry, (4) Organic Chemistry, (5) Biological

Chemistry,

Theoretical Chemistry is primarily concerned with the ultimate goal of

chemistry: the structure of matter, and from this knowledge the explanations of itstransformations from one form into another. Since the examination of energy

changes is helpful in the pursuit of this goal, the term Physical Chemistry is

sometimes used. Theoretical or Physical Chemistry is the investigation of the laws

and theories of all chemistry.

Analytical Chemistry is the experimental foundation of chemistry. Without it

little could be accomplished in any branch of the science. It is concerned with the

separation, identification, and composition of various kinds of matter. For example,

Qualitative Analysis provides methods of finding out whether a given sample of

matter contains lead or gold. It separates and identifies. Quantitative Analysis

answers the question "How much gold or lead?"

Again, merely for convenience, chemistry is frequently divided into Inorganic

and Organic Chemistry. One reason for this division is that one element, carbon,

forms many more compounds than most of the other elements. The chemistry of

carbon compounds is called Organic Chemistry; the remaining is called Inorganic

Chemistry.





I. Vocabulary in context: Put the words / phrases into the blanks

experimental foundation - overview - the structure of matter – transformations -energy changes - scientific study - carbon compounds – composed -

atoms - five - molecules

1. Chemistry is the …………………..of the substances that wake up the

universe.

2. Elements are work up units called …………….

3. When atoms combine, they usually form units called ………………..

4. Chemistry hopes to know that matter is ………….of, and how its

…………………. from one form into another are relate to its composition.

5. There are ………..subcategories of chemistry.

6. Theoretical chemistry is primary concerned with ………………………….

7. Physical chemistry is concerned with the examination of ………………...

8. Analytical chemistry is the …………………………………. of chemistry.

9. The study of substances containing …………………. is called organic

chemistry.

10. This unit is an ……………….. of a science called chemistry.

II. Comprehension question:1. What do scientist attempt to investigate in the field of chemistry? …………

………………………………………………………………………………….

2. What are Chemical compound made of, in general? …………………….….

…………………………………………………………………………………..

3. What can we benefit from the attempt of scientists trying to study the nature

of matter? ………………………………………………………………………

………………………………………………………………………………….

4. What can scientist obtain if they understand the structure of matter? …………………………………………………………………………………………..

5. What is the main reason for the appearance of organic chemistry? …………

…………………………………………………………………………………..

III. Vocabulary in new context: Put the words / phrases into the blanksinorganic chemistry – molecules - Analytical chemistry -

study of chemistry - organic chemistry - elements





1. The ……………………………. is the study every substance, its structure,

its composition and reactions in which it takes part.

2. The over whelming variety of materials occurring in nature are made upfrom ninety-two basic ingredients called ………………..

3. Atoms join together to form what we call …………………..

4. Nearly half a million compounds are known to contain the element carbon,

and they are given a branch of chemistry to themselves called ………………...

5. The study of elements other than carbon is called …………………….

6. …………………………. is concerned units the identification of the various

ingredients of a compound (qualitative analysis) and finding out the quantity of

each present (quantitative analysis).

WORD STUDYWe can sometimes add a prefix to the beginning of some words. In this

case the new word will have the opposite meaning to the original one

Some of the prefixes are: un-, im-, in-, did-, non-

Example:

Un- healthy => unhealthy

Smoking is not good for you. It’s unhealthy

Here are some other words with these negative meaning

Un- unimportant, unpopular

Im- impossible, impolite

In- incomplete, incredible

Dis- discontinue, disagree

Non- nonfat, nonsmoking

Circle the letter of the best word to complete each sentence

1. A person who is unfriendly is probably……………….., too.

a. unpopular b. unusually

2. The service at this restaurant is very slow. It’s …….to have a quick lunch.

a. impossible b. important

3. The airline will ……..service to that city. It is not a popular place to go.

a. discontinue b. disagree

4. ………………yogurt is better for you than ice-cream





a. nonstop b. nonfat

5. Tom’s homework is ………because he felt sick last night

a. inexpensive b. incomplete

Can you find some other words with those above prefixes? List them in

here: ………………………………………………………………………………

…………………………………………………………………………………….. ..

IV. Grammar review:A. Present Simple tense:

In general, the Simple Present expresses events or situation that exist always,

usually, and habitually; they exist now, have existed, and probably will existin the future.

The most frequent tense in science is simple present.

Example :

A water molecule consist s of two hydrogen atoms and one oxygen atom

Or

Electrons spin around the nucleus.

Formation:

To form the simple present, use the simple form of the verb for most forms.

Add -s or -es only to the third-person singular.

Example:

Chemistry seeks the answer to two questions.

Chemists investigate the properties of substances and how different

conditions affect the way substances behave.

Put the verb in the parentheses into correct forms:

1. Electrons (move) …………….along many paths called orbitals.2. The periodic table (organize) ……………elements in specific vertical

and horizontal rows.

3. Each vertical column of the periodic table (include)……………. element

that are chemically related.

4. Groups of elements in the periodic table (tend)………………. to show

similar properties.





5. Hydrogen (form) ……………… many compounds and (have)

…………..many uses.

6. In a liquid, molecules (move about)………………. easily, but they still(have) ………… some force that (attract) …………….them to one another

called surface tension .

7. Molecules (occur)……………. in an incredible number of shapes and

sizes.

8. Liquids (freeze)…………….. and gases (condense)……………… at

certain temperatures.

9. By studying the chemical properties of compound, chemists (be able to)

…………………… create new and useful substance and to understand the

chemical process that take place in nature everyday.

10. Chemistry (be)……………. the scientific study of the substances that

make up the universe.

B. Past Simple tense:

The Simple Past describes actions and events that were complete at a definite

time in the past . The situations and actions way be recent or a long time ago,

habitual, short or long.

* All regular Simple Past verbs end in -ed.

* Irregular verbs have different forms, so you have to learn by heart

Example :

Several philosophers of the Graeco -Roman civilization time proposed

various substances out of which they regarded the universe as having

been constructed.

The principle "elements" suggested were water, air, fire, and earth.

Put the verbs in parentheses into correct form:

1. During the 1600’s, an Irish scientist named Robert Boyle (conduct)

……………. a series of experiments that (disprove) …………… the theory

that air, earth, fire, and water (be) …………. the basic element of matter.

2. Boyle's work (change)…………. the course of chemistry because

scientists (begin)…………. to recognize that certain familiar substances

(can)…………… not be broken down into simpler substances - therefore,

they must be elements.





3. During the first 300 years after the birth of Christ, scholars and craft

workers in Egypt (develop)……………….. a chemical practice that

(come)………….. to be called alchemy.4. Chemists (continue)………………. to have difficulty categorizing the

elements until 1869.

5. Late 1700's Antoine Lavoisier (write)……………… the first modern text

book on chemistry.

C. The Present Perfect tense:

The Present Perfect is used to express past time that is related to the present

in someway. Sometimes the past action is very recent, or it is still continuing

at the present moment, or we don't know exactly when the past action

happened, we only know that it happened sometime in the past.

To form the present perfect, use the Simple Present form of have + the past

participle of the main verb.

Example:

Chemists have tried to develop a full understanding of all substances.

Chemistry has been a very important course in school.

FURTHER EXERCISES ON GRAMMAR:Use either the SIMPLE PRESENT or PRESENT PROGRESSIVE of the

verbs in parentheses:

Tim (have)………….. a car.

Tim (have)…………. trouble with his car, so he has to take the bus to work

these days.

This box (weigh)…………… a lot. It’s too heavy for me to lift.

I just handed the box to the postal worker. Right now she (weigh) ……………..

……it to see how much postage it (need) …………….

I (do)……………… this practice at the moment. It consists of both non-

progressive and progressive verbs.

I (think)…………………. about the verbs in this grammar practice right now. I

(think)……………….. all of my answers are correct, but I’ll use the answer

key to check them when I finish to make sure.

Mrs. Edwards is at the market. Right now she (look)…………………. at the

apples. They (look)……………….fresh.





Right now Martha is in the science building. The chemistry experiment she is

doing is dangerous, so she (be)…………………very careful. She (want, not)

…………………to spill any of the acid. She (be, always)……………….careful when she does a chemistry experiment.

Dennis (drink, usually)……………coffee with his breakfast, but this morning he

(drink)……………….tea instead.

This morning, it (rain)………….. I can see Janet from my window. She

(stand)……………at the corner of 5th

and pine. She (hold)……………. Her

umbrella over her head. She (wait)…………………for the bus.

Use either the SIMPLE PAST or PRESENT PERFECT of the verbs in

parentheses:

1. I (know) ……………….…Tim when I (be)………..…….. a child, but I havenot seen him for years.

2. The company and the union finally (agree)…………….……….on

everything, and the rest of the negotiation have gone smoothly.

3. Mark (take)………………a trip to Asia last October. He (take)…………….

to Asia since he started his own import-export business.

4. Ivan (play)…………………….the violin with the London Symphony since

1985. Last year he (play)…………………..a Beethoven violin concerto at

the concert..5. When she was in college, Julia (write)…………………….home at least once

a week. Now she has a job and is living in Chicago. In the last six months,

she (write)…………….……only three letters to her parents.

6. Our university (send) …………..………..210 students to study in other

countries last year. In total, we (send) ………..………….846 students abroad

over the last ten years.

7. Maseru is a pilot for France Air Lines. He (fly) ……….…………nearly 8

million miles during the last years. Last years, he (fly)…………..………203

miles.8. Mark missed his physics examination because he (oversleep)………….. He

(oversleep)………………..….a lot since the beginning of the semester. He’d

better buy a new alarm clock.

9. Alex is an artist. He (draw)………………………..many beautiful pictures in

his lifetimes. Last week, he (draw)…………..…………….a beautiful

mountain scene.





10. Jack recently needs to get in touch with you. Since this morning, he

(call)………………… here four times trying to reach you. He (call)………..

at 9:00, 10:15, 12;15 and 1:45.11. Janet (wear) …………………….………….her new blue dress only once

since she bought it. She (wear)…………….………………..it to her brother’s

wedding.

12. The night has ended and it’s daylight now. The sun (rise)…………………at

6:06





UNIT TWO: ATOMSAll things are made up of basic units of matter called atoms. Atoms vary greatly

in weight, but they are all about the same size-more than a million times smaller

than the thickness of a human hair. Yet tiny as they are, atoms consist of even more

minute subatomic particles. The three basic types of these particles are called

protons, neutrons, and electrons. Proton and neutrons form the nucleus, or center, of

the atom. Nuclei is the term for more than one nucleus. Electrons whirl around the

nucleus.

Atoms are the building blocks of the chemical elements, the simplest substances.

Hydrogen and lead are examples of well-known elements. Each element has a

unique type of atom: Atoms of different elements vary according to their number of

protons. A hydrogen atom, for example, has 1 proton, while an atom of lead has S2.Electricity binds the parts of an atom together. Protons in the nucleus carry a

positive electric charge, and electrons rotating around the nucleus carry a negative

charge. Neutrons have no charge, and so do not affect the electricity of the atom.

Ordinarily, atoms have the same number of protons and electrons. As a result, there

is a balance in each atom that makes it electrically neutral. But because opposite

charges attract, the atom could collapse in on itself. Additional energy in the

electrons keeps them spinning around, which prevents the atom from collapsing.

And a force called strong nuclear force keeps the protons and neutrons contained

within the nucleus.

I. Vocabulary in context:

opposite charges attraction - strong nuclear force - electricity - negative - number

of protons - neutrons - subatomic particles - electrons - atoms - protons - positive -

additional energy - no charge - protons and electrons -

1. All things are mode up basic units of matter called ……………...

2. Atoms consist of three basic ……………….

3. Three basic types of particles are …………, …………, and ………………...

4. Atoms of different element are different from one another depending on their

………………………..

5. Protons carry a ……………..electric charge, while electrons carry a ………..

charge

6. Neutrons have …………….., and so do not affect the ……………. of the

atom.





7. Normally, the number of ……………………….is equal.

8. Due to …………………………………, the atom could collapse in itself.

9. Thanks to …………………….……….., electrons can spin around the

nucleus, which prevent the atom from collapsing.

10. The fact that protons and neutrons can stay within the nucleus is thanks to a

force called …………………………………...

II. Vocabulary in new context:

chemical reactions - protons - positive - molecules - atom – nucleus – atoms - a

group of atoms - Atoms - Electrons - protons - neutrons

1. All matter is made of ………….., the smallest bit of each element.

2. A particle of gas could be an ………..or ………………...

3. …………..have energy of motion that we feel as temperature.

4. The motion of atoms or …………….can be in the form of linear motion of

translation, the vibration of atoms molecules against one another or pulling

against a bond.

5. ……………………spin around the nucleus rapidly.

6. Every atom of a particular element has the same number of ……………….

7. Electrons are much smaller than ………………or ………………….

8. The concept of atoms and molecules enables us to understand more fully the

…………………………..

9. The nucleus contains small heavy particles called protons, which possess the

……………….charge and other small particles called neutrons which have thesame mass as the protons but have no charge at all.

10. At the center of every atom lies the core or …………………, which is very

small compared with the size of the atom as a whole.

III. Comprehension questions: Write T if the following statement istrue, and F if false.

1. Atoms are the most basic units of substance _____





2. A force called strong nuclear fore helps the protons and neutrons stay

together within the nuclear _____

3. Neutrons have positive electric charge_____

4. Protons have positive electric charge_____

5. Electrons go around the nucleus _____

6. Electrons have no electric charge _____

7. An atom could collapse in on itself _____

8. Thanks to an additional energy, electrons can which around the nucleus ___

IV. Grammar: PASSIVE VOICE STRUCTURE

The passive is most frequently used when we do not know or it is not important to

know exactly who performs an action, or when we want to emphasize the role of the

now used as subject in passive voice.

In the passive, the object of an active verb becomes the subject of the passive verb.

Example:

Chemistry is frequently divided into Inorganic and organic chemistry we do

not know and it is not important to know who know divide chemistry into

branches.

Elements are made up units called atoms

Passive form is formed as: Noun / Noun Phrase + Be + V pp + (by …)

Turn the following sentences into passive voice:

Without knowledge of analytical chemistry, we could accomplish little in any

branch of the science.

…………………………………………………………………………………

…………………………………………………………………………………

Scientist call the chemistry of carbon compounds Organic Chemistry.

…………………………………………………………………………………

Scientists often compare the structure of an atom with that of the solar system.





…………………………………………………………………………………

………………………………………………………………………………..

We can beak protons and neutrons down into ever smaller particles calledquarks.

…………………………………………………………………………………

………………………………………………………………………………..

Electron in the outer shells control the chemical behavior of an atom.

…………………………………………………………………………………

The behavior of the atoms that make up a substance determines the behavior of

that substance.

……………………………………………………………………………………………………………………………………………………………………

Since 1964, several groups of scientists claimed that they had created six new

elements.

…………………………………………………………………………………

………………………………………………………………………………..

Although molecules are made up of atoms, scientists still consider them

(molecules) one of the basis units of matter.

……………………………………………………………………………………………………………………………………………………………………

People usually classify chemical elements as mental or non-mental.

…………………………………………………………………………………

Antoine Lavoisier wrote the first modern textbook on chemistry.

………………………………………………………………………………….

Put the verb in brackets into correct form

1. The three basis types of subatomic particles (call) ______ protons, neutrons,

and electrons.

2. Elements (make up of) ________________units called atoms

3. Theoretical chemistry (concern) ________primarily _________with the

ultimate goal of chemistry the structure of matter.

4. Analytical chemistry (concern) _________with the separation,

identification, and composition of various kinds of matter.

5. The chemistry of carbon compounds (call) _________Organic Chemistry.





6. All the matter around you (make up) ____________atoms.

7. The electrons associated with atoms (find) ___________to have measurable

properties which exhibit quantization.

8. It (believe) _______________that air, earth, fire and water were the basic

elements of matter.

9. Symbols for the elements (may use) _____________merely as abbreviations

for the name of the element.

10. But they (use) ______________more commonly in formulas and equations

to represent a fixed relative quantity of the element.

FURTHER EXERCISES ON PASSIVEChange the sentences into passive forms; make sure the meaning of the original

sentences is the same.

The waiter refilled my glass.

………………………………….…………………………..…………………..

Did Sue knock that vase at the door?

………………………………………………to the floor by Sue?

The pollution I the city was affecting Tim’s breathing.…………………………………………………………………….……………..

Had a special messenger delivered the package before you got to the office?

……………………………………………………………….………………….

Mr. Snow hasn’t taught that course since 1985.

…………………………………………………………………….……………..

The city attorney has discovered new evidence.

……………….……………………………………………………………………

The voters are going to decide that issue.

……………………………………………………………………..……………..

Your emotional appeals will not influence the judge.…………………………………………………………………………………….

The best chess player will win the match.

…………………………………………………………………………………..

Is a student pilot flying that airplane?

…………………………………………………………………………………….

Complete the sentences with the words in brackets. Some tenses are active and

some passive

You (notify) ……………………by my secretary next week.

Last night I (remember, not)……………………….to lock the front door.





At the present time, the oldest house in town (restore) ………………..by the

History Society. When the restoration is finished, the house is sure to be a

popular tourist attraction.A: What a beautiful old wooden chest!

B: It (build) ……………………….by my grandfather over 50 years ago.

At one time, the entire world (rule) …………………..by dinosaurs. Some

dinosaurs (walk) …………………..on their hind legs and (stand) …………..

as tall as palm trees.

Disney land is a world famous amusement park in Southern California. It

(visit)………………by more then ten million people every year.

Many of us take water for granted in our daily lives, but people who live in the

desert (use, not)…………….……..water carelessly. To them, each drop is

precious.I (agree, not)………………….with people who say space exploration is a waste

of money. What do you think?

Do you really think we (invade) …………………by creatures from outer space

in a near future?

Most insects (live)………………..for less than a year. The common housefly

(live) ………………..from 19 to 30 days.

(You, accept, already)………………………by this university when you heard

about the other scholarship?

I got into a taxi quickly because I (follow)…………………by two strange men.

As soon as o got into the taxi, I (feel)……………a little safer.The impact of the earthquake yesterday (feel)……………..by people who lived

hundreds of kilometers from the epicenter.

Mark (influence)………………….a lot by his friends, isn’t he? He should be

more independent and think for himself.

WORD STUDY: The prefix re- means ‘to do something again’.

For example: re + do => redo (to do again)

re + read => reread (to read again)

Add the prefix re- to each word. Then choose the correct word to complete each

sentence: arrange, do, order, tell, build, married, take, write

Jose made many mistakes in his first composition. Before he gives it to histeacher tomorrow, he is going to …………it.

Dave and Susan got divorced 10 years ago. Last year Susan got ……… and

moved to Canada with her new husband.

I think I should ……………the furniture in my apartment. The way I have the

tables and chairs makes the room look crowded.

Children love to hear their grandparents tell stories! They often ask their

grandparents to …………their favorite stories many times.

The new waiter at the restaurant forgot our order for dinner, so we had to ….

everything.





If you do not get good score on the TOEFL exam this weekend, you can ….. it

next month

FURTHER READINGSThe Nature of the Problem

The understanding and prediction of the properties of matter at the atomic level

represents one of the great achievements of twentieth-century science. The theory

developed to describe the behavior of electrons, atoms and molecules differs

radically from familiar Newtonian physics, the physics governing the motions of

macroscopic bodies and the physical events of our everyday experiences. The

discovery and formulation of the fundamental concepts of atomic physics in the

period 1901 to 1926 by such men as Planck, Einstein, de Broglie and Heisenbergcaused what can only be described as a revolution in the then-accepted basic

concepts of physics.

The new theory is called quantum theory or quantum mechanics. As far as we

now know this theory is able to account for all observable behavior of matter and,

with suitable extensions, for the interaction of matter with light. The proper

formulation of quantum mechanics and its application to a specific problem requires

a rather elaborate mathematical framework, as do proper statements and applications

of Newtonian physics. We may, however, in this introductory account acquaint

ourselves with the critical experiments which led to the formulation of quantummechanics and apply the basic concepts of this new mechanics to the study of

electrons.

Specifically the problem we set ourselves is to discover the physical laws

governing the behavior of electrons and then apply these laws to determine how the

electrons are arranged when bound to nuclei to form atoms and molecules. This

arrangement of electrons is termed the electronic structure of the atom or molecule.

Furthermore, we shall discuss the relationship between the electronic structure of an

atom and its physical properties, and how the electronic structure is changed during

a chemical reaction.

Rutherford's nuclear model for the atom set the stage for the understanding of the

structure of atoms and the forces holding them together.

From Rutherford's alpha-scattering experiments it was clear that the atom

consisted of a positively-charged nucleus with negatively-charged electrons

arranged in some fashion around it, the electrons occupying a volume of space many

times larger than that occupied by the nucleus. (The diameters of nuclei fall in the





range of l × 10-12

→ 1 × 10-13

cm, while the diameter of an atom is typically of the

order of magnitude of 1 × 10-8

cm.) The forces responsible for binding the atom,

and in fact all matter (aside from the nuclei themselves), are electrostatic in origin:the positively-charged nucleus attracts the negatively-charged electrons. There are

attendant magnetic forces which arise from the motions of the charged particles.

These magnetic forces give rise to many important physical phenomena, but they

are smaller in magnitude than are the electrostatic forces and they are not

responsible for the binding found in matter.

During a chemical reaction only the number and arrangement of the electrons are

changed, the nucleus remaining unaltered. The unchanging charge of the atomic

nucleus is responsible for retaining the atom's chemical identity through any

chemical reaction. Thus for the purpose of understanding the chemical propertiesand behavior of atoms, the nucleus may be regarded as simply a point charge of

constant magnitude for a given element, giving rise to a central field of force which

binds the electrons to the atom.

Rutherford proposed his nuclear model of the atom in 1911, some fifteen years

before the formulation of quantum mechanics. Consequently his model, when first

proposed, posed a dilemma for classical physics. The nuclear model, based as it was

on experimental observations, had to be essentially correct, yet all attempts to

account for the stability of such a system using Newtonian mechanics ended in

failure.

According to Newtonian mechanics we should be able to obtain a complete

solution to the problem of the electronic structure of atoms once the nature of the

force between the nucleus and the electron is known. The electrostatic force

operative in the atom is well understood and is described by Coulomb's law, which

states that the force between two particles with charges e1 and e2 separated by a

distance R is given by:

There is a theorem of electrostatics which states that no stationary arrangement of

charged particles can ever be in electrostatic equilibrium, i.e., be stable to any

further change in their position. This means that all the particles in a collection of

postively and negatively charged species will always have resultant forces of

attraction or repulsion acting on them no matter how they are arranged in space.

Thus no model of the atom which invokes some stationary arrangement of the

electrons around the nucleus is possible. The electrons must be in motion if





electrostatic stability is to be preserved. However, an electron moving in the field of

a nucleus experiences a force and, according to Newton's second law of motion,

would be accelerated. The laws of electrodynamics state that an accelerated charged particle should emit light and thus continuously lose energy. In this dynamical

model of the atom, all of the electrons would spiral into the nucleus with the

emission of light and all matter would collapse to a much smaller volume, the

volume occupied by the nuclei.

No one was able to devise a theoretical model based on Newtonian, or what is

now called classical mechanics, which would explain the electrostatic stability of

atoms. The inescapable conclusion was that the classical equations of motion did not

apply to the electron. Indeed, by the early 1900's a number of physical phenomena

dealing with light and with events on the atomic level were found to be inexplicablein terms of classical mechanics. It became increasingly clear that Newtonian

mechanics, while predicting with precision the motions of masses ranging in size

from stars to microscopic particles, could not predict the behavior of particles of the

extremely small masses encountered in the atomic domain. The need for a new set

of laws was indicated

Questions

What do we – human being benefit from the understanding and prediction of the

properties of matter at the atomic level?

What does the quantum theory or quantum mechanics concern about?

What are the main differences between Newtonian mechanics and quantum

mechanics?





What does the theorem1 of electrostatics

2 concern?

How does the text end? What does it say about Newtonian mechanics?

1 Ñònh lyù, quy taéc2 Tónh ñieän hoïc





UNIT THREE: STRUCTURE OF AN ATOMAtoms behave as if they were solid. Electrons spin around the nucleus at such

amazing speed that they create the effect of a rigid exterior. But most of an atom is

actually made up of empty space. The nucleus fills only the tiniest portion of that

space, and the nucleus is proportionately very distant from the orbiting electrons.

For example, if a hydrogen atom were about 4 miles (6.4 kilometers) in diameter, its

nucleus would be no bigger than a tennis ball.

The structure of an atom is often compared with that of the solar system,

suggesting that electrons orbit the nucleus just as planets orbit the sun. But this is

not a completely accurate comparison, because atoms are not nearly as orderly as

the solar system. Electrons do not follow regular paths, and protons and neutrons

move about constantly within the nucleus. The subatomic particles do, however,show certain patterns of behavior.

THE NUCLEUS, in spite of its small size, makes up nearly all the mass of an

atom. Protons and neutrons compose the nucleus of all atoms except the most

common form of hydrogen, which has only a proton at its center. Protons are just

slightly smaller than neutrons, and both particles are about 100,000 times smaller

than an entire atom.

Every atom of a particular element has the same number of protons. The number

of neutrons, however, may vary. Atoms that have the same number of protons but

different numbers of neutrons are called isotopes. The number of neutrons does notusually affect how an atom behaves in reactions.

Protons and neutrons can be broken down into even tinier particles called quarks.

Each proton and neutron consists of three quarks.

ELECTRONS are the vital components of every chemical reaction. Chemistry,

therefore, is particularly concerned with the behavior of electrons, particularly in

relation to electrons of other atoms.

Electrons are much smaller than protons or neutrons. They have very little mass

and do not seem to be made up of smaller parts. However, electrons occupy almost

the entire volume of an atom, traveling through the space around the nucleus, andcompleting billions of trips each millionth of a second.

Electrons move along wavy paths, called orbitals, which may appear as any one

of a variety of rounded shapes. Each electron carries a certain amount of energy.

Those with greater energy are located farther from the nucleus. Electrons are

arranged according to their energy level in shells, which are at different average

distances from the nucleus.

Each electron shell is designated by a number-the shell closest to the nucleus is

called shell 1, and the others are called 2, 3, 4, 5, 6, and 7, in order of their







III. Answer the questions1. Do electrons go around the nucleus? …………………………………………

………………………………………………………………………………..

2. Do they follow the same paths?………………………………………………

……………………………………………………………………………….

3. What makes up the mass of an atom?…………………………………………

4. What is isotope?……………………………………………………………….

…………………………………………………………………………………

5. What is orbital? ………………………………………………………………

…………………………………………………………………………………

6. Do electrons have energy? …………………………………………………..

………………………………………………………………………………..

7. How are electrons arranged? …………………………………………………

………………………………………………………………………………..

8. Do all atoms have the same number of shells? ………………………………

……………………………………………………………………………….

9. What determines the chemical behavior of an atom? ……………………….

………………………………………………………………………………..

10. What is the main idea of this text? …………………………………………..

………………………………………………………………………………..

IV. Structure: Passive (continued)

PUT THE VERBS IN BRACKETS IN PASSIVE FORM

1. Interestingly, Helium first (discover)_____________, not on our world, but on the sun

2. Ionic bond (form) _____________by the electrostatic attraction after the

complete transfer of an electron from a donor atom to an acceptor atom.

3. Electrons (can transfer) _____________carrying energy to another

molecule.





4. Molecules (make up of) ______________atoms held together in certain

arrangements.

5. The chemical formula for water (write) __________________as H2O

FURTHER EXERCISERS: CHANGE THE SENTENCESINTO PASSIVE. INCLUDE ‘ BY PHRASE’ IF

NECESSARY

People grow rice in India …………………………………………………

My aunt made this rug …………………………………………………….

They are fixing my car to day ……………………………………………..

They speak French in Quebec. ……………………………………………

Mr. Edwards designed that bridge inn 1970’s ……………………………

Did Thomas Edison invent the telephone? ………………………………..

Someone invented the wheel thousands of years ago …………………….

They are going to build a new hospital just outside of town ……………...

How do people make candles? …………………………………………..

Have you broken that vase? ……………………………………………

WORD STUDY - SUFFIXES

The suffix – less means “without” or “not having something”

Here is an example:

The number of English words to learn is endless (without end)

Add the suffix –less to each word. Then choose the best word for each

sentence:

Care ……………………… Change …………………………..

Hope ……………………. Worth …………………………..





Help ……………………. Thought ………………………….

End ……………………… Sleep …………………………….

Babies cannot take care of themselves. Someone most help them because

they are ……………………

Stephen found an old coin. He thought it was gold, but it wasn’t. in fact, it

had no value. It was ………………………

You must take your time and be careful when you wrote. If you try to hurry,

you will make ………………mistakes.

Alice was sick last night so she could not sleep. Today in class she was verytired after such a ………….night.

Helen said nothing that hurt my feelings. I know she did not want to hurt my

feelings. She just was not thinking. She made a ……………mistake.

Most students are making a good progress but Jeremy seems a ……… case.

He does not have any improvement at all.

Wow, I have not seen you for ages, but you look the same as before. You are

……………..

Timmy had many accidents since the day he got his new car. He is a

…………………. Driver.

I will always love you, darling. My love for you is ……………….

I spent many ………………night thinking about you, wondering if you love

me truly.













7. What happens when an atom loses electrons? When an atom gains electrons?

…………………………………………………………………………………

………………………………………………………………………………….8. What does valence refer to? ……………………………………………………

9. When does an atom have a positive valence? ………………………………….

………………………………………………………………………………….

10. When does an atom have a negative valence? …………………………………

………………………………………………………………………………….

III. GrammarTypes of sentences

Single sentence or independent clause: A simple sentence has single subject

– verb combination. It usually has one subjects, but sometimes there may

be more than one subject.

Example:

All matter is made up atoms

There are two types of property of water: physical properties and chemical

properties.

All simple end by a stop (.) or a semicolon (;).

Compound sentences

A compound sentence is made up two (or sometimes more) simple

sentences that are joined by a conjunction (such as “for”, “and”, “nor”,

“but”, “or”, “yet”, “so”).

For example:

Some of the symbols have one letter, and some have two.

Symbols for the elements may be used merely as abbreviations

for the name of the element, but they are used more commonly

in formulas and equations to represent a fixed relative quantityof the element

Complex sentences:

Complex sentences are made up one or more independent clauses and one

or more dependent clauses.

For example:

Because opposite changes attract, the atom could collapse in

on itself





Because … changes attract: dependent clauses

the atom … collapse in on itself: independent clauses.

Although molecules are made up atoms , they are still

considered one of the basic units of matter (unit 6)

Although …atom: dependent clauses

They are …matter: independent clauses

The atom could collapse in on itself because opposite charges

in the atom attract each other

The atom …itself: independent clauses

because …each other: dependent clauses

Dependent clauses usually start with words like when, while, where,

because, although, if, etc.

Write independent if the following sentences are Independent, Compound, or

Complex:

1. Chemistry seeks the answer to two question (unit 1) ……………………….

2. The chemistry of carbon compound is called organic chemistry (unit 1) …..

3. Atoms vary greatly in weight, but they are all about the same size-more

than a million times smaller than the thickness of a human hair (unit 2) …..

4. if a hydrogen atom were about 4 miles (6.4 kilometers) in diameter, its

nucleus would be no bigger than a tennis ball (unit 3) ………………….

5. Atoms that have the same number of protons but different numbers of

neutrons are called isotope (unit 3) ……………………………………

6. Electrons in the outer shells control the chemical behavior of an atom (unit

3) ……..

7. If you see the symbol of an element, you should know the name of that

element……………………..8. When they join with other elements, non-metals can either share electrons

in a covalent bond or gain electrons to become a negative iron to make an

ionic bend. ………………………..

9. Although all matter consists of chemical element, very little of the matter

on Earth is made up of elements in their pure or uncombined form……….

10. A solution is said to be dilute if there is les of the solute…………………..

Combine the following sentences









13. Molecules / occur in / incredible number / shapes and sizes.

…………………………………………………………………………………

14. A compound / a substance / that / made up of at least two different elements

…………………………………………………………………………………

15. Blood / many other fluids in living things / colloids.

…………………………………………………………………………………





UNIT FIVE: ELEMENTS AND SYMBOLS OF ELEMENTSChemical elements, the most basic of substances, can be defined in either of two

ways. An element is (1) a substance that cannot be broken down chemically into a

simpler substance, or (2) a substance that contains only one kind of atom.

All chemical substances are either elements or compounds, which are

combinations of elements. For example, hydrogen and oxygen are elements, and

water is a compound of hydrogen and oxygen. A few elements occur naturally in

their pure form. They include carbon, sulfur, and certain metals, such as gold and

silver. But nearly all other elements - apart from the gases in the atmosphere - occur

in combination as compounds.

There are currently 103 officially named and recognized elements. Some

elements do not occur naturally and must be created in a laboratory. Since 1964,several groups of scientists have claimed to have created six new elements, but none

of the claim has yet been accepted officially.

The names of elements come from different sources. Some of these names come

from Greek or Latin words. Bromine, for example, gets its name from the Greek

word for stench. Many artificially created elements are named in honor of a place or

individual. Einsteinium, an element created in a laboratory, was named in honor of

the physicist Albert Einstein.

Each element has a symbol that consists of one or two letters. Chemists use these

symbols as abbreviations for elements. The symbols are universally recognized, andso provide an international language for chemists.

In some cases, the first letter of an element's name is used as its symbol. For

example, C is the symbol for carbon. If the names of two or more elements begin

with the same letter, two letters of a name are used for all but one of the elements.

The second letter is written in lower case. The symbol for calcium is Ca, and the

symbol for helium is lie. Some symbols come from an old word for the element.

Sodium, for example, has the symbol Na, which comes from the Latin word for

sodium, natrium.

Chemists use the symbols for elements to write formulas for compounds. Theformulas tell which elements and how many atoms of each are in a compound.

Chemical reactions can be illustrated by placing the formulas in a particular series.

There are only a few more than one hundred elements. Of those, only eighty-

three are not naturally radioactive, and of those, only fifty or so are common enough

to our experience to be useful for general knowledge.

It would serve you well to know the elements. If you were to attempt to read

anything without knowing your letters, you would be in trouble. Let’s say you still

have a hard time telling the difference between a ‘b’ and a ‘d’. Your fluency in







4. they are used more commonly in ……………and equations too represent a

fixed relative quantity of the element.

5. …………………….and ……………..are used to describe chemicalreactions.

III. Comprehension questions1. According to the text, what is a definition of element? ……………………..

…………………………………………………………………………………..

2. Under what forms do all chemical substances exist? ……………………….

………………………………………………………………………………….

3. How many elements are worldwide recognized? ……………………………

…………………………………………………………………………………..

4. How do scientists represent a name of an element so as all people can

recognize the element represented? ……………………………………………

………………………………………………………………………………….

5. Apart from being recognized universally, what are the symbols for the

elements are used for? …………………………………………………………..

…………………………………………………………………………………..

IV. Grammar: Relative Clauses (review)

• That / Which

Example:

An element is a substance. The substance cannot be broken down

chemically into a simpler substance.

=> An element is a substance that/which cannot be broken down

chemically into a simpler substance.

1. The formulas tell us something. They tell which elements and how many

atoms of each are in a compound.

…………………………………………………………………………………………………………………………………………………………………….

2. You find in each box of the Periodic Chart an integer. The integer is the

atomic number

……………………………………………………………………………………

………………………………………………………………………………

3. Each vertical column of the periodic table includes elements. These elements

are chemically related.





……………………………………………………………………………………

…………………………………………………………………………………..

4. Elements in Group I of the periodic table are very soft metals. They are notfound free in nature because they react with water.

……………………………………………………………………………………

…………………………………………………………………………………..

5. Natural elements have atomic numbers. The atomic numbers range

successively up to 92.

……………………………………………………………………………………

…………………………………………………………………………………..

• If / When / While1. You see the symbol of an element. You should know the name of that

element.

If…………………………………………………………………………………

………………………………………………………………………………..

2. The hydrogen electron energy levels are found to depend only upon the

principal quantum number . The energy levels in other atoms are found to

have strong dependence upon the orbital quantum number .

While………………………………………………………………………………

………………………………………………………………………………

3. An atom has 6 protons. It is carbon

If …………………………………………………………………………………

4. Two atoms have the same number but different atomic weights. They are said

to be isotopes.

When………………………………………………………………………………

………………………………………………………………………………..

5. Electrons in the outer shells control the chemical behavior of an atom.. these

electrons can react with other atoms.

Because……………………………………………………………………………

…………………………………………………………………………………

• Further exercises on combining sentences

1. Scientists have discovered something. They discovered that the rare gases

are found as gases at ordinary temperatures and pressures.

http://c3/

http://c1/

http://c1/

http://c3/





…………………………………………………………………………………

…………………………………………………………………………………

2. Helium is best known as gas in balloons and airships. Helium is used to prevent chemical from reacting with other elements during storage and

transportation.

…………………………………………………………………………………

…………………………………………………………………………………

3. There is a force. It is called van de Waals. It holds molecules together.

…………………………………………………………………………………

..………………………………………………………………………………

4. Van de Waals is a force. It holds molecules together. It is usually weaker than

the forces that hold the atoms of a molecules together.…………………………………………………………………………………

…………………………………………………………………………………

5. The theory of spontaneous suggests one idea. The idea is that life suddenly

arose from nonliving matter.

…………………………………………………………………………………

…………………………………………………………………………………

6. WORD STUDY

7.

The prefix over- means “too,” “too much,” or “too many.”8. Look at the example:

9. The cities in developing countries are already overcrowded. (too

crowded)

10. Add the prefix over- to each word. Then choose the best word for each

sentence:

11. Eat …………………….

12. Populated ……………………

13. Wight ……………………

14. Heated ……………………15. Slept ……………………

16. Cooked ……………………

17. 1. There are too man people on the island of Java in Indonesia. Java is ……..

18. 2. We were driving in the mountains on a very hot day, and our car ………..

We had to stop and let it cool down.

19. 3. Mary left the rice in the cooker too long. Now the rice is ………………..







Further readings

THE PERIODIC TABLE OF ELEMENTSDuring the 1700's and 1800's, scientists concentrated on gathering information

about the characteristics of the elements known at that lime. They soon found that

there were similarities between some elements, both in their properties and in the

way that they form compounds. This information enabled scientists to predict

chemical behavior more accurately. Eventually, scientists developed the periodic

table of elements, which arranges elements according to their properties and

provides a quick reference for essential chemical information.

The periodic table organizes elements in specific vertical and horizontal rows.

Elements run horizontally across the table in order of increasing atomic number.Each element has one more proton in its nucleus than the element on its left, but one

less than the element on its right. These horizontal rows are called periods.

Each vertical column of the periodic table includes elements that are chemically

related. These groups of elements tend to show similar properties, particularly in

forming compounds. In most cases, the elements in a group have atoms with the

same number of electrons in their outer shells. However, atoms of elements in the

same group vary greatly in total number of electrons. A complete periodic table

provides the following basic information about each element:

• name

• chemical symbol

• atomic number

• atomic mass or mass number

• number of electrons in each shell of its atom

• chemical group to which it belongs

Group I (1) elements, lithium, sodium, potassium, rubidium, cesium, and

francium, are also called the alkali metal elements. They are all very soft metals that

are not found free in nature because they react with water. In the element form theymust be stored under kerosene to keep them from reacting with the humidity in the

air. They all have a valence of plus one because they have one and only one electron

in the outside shell. All of the alkali metals show a distinctive color when their

compounds are put into a flame. Spectroscopy (dividing up the spectrum so you can

see the individual frequencies) of the colored light from the flame test shows strong

emission lines from the elements. The lightest of them are the least reactive.

Activity increases as the element is further down the Periodic Chart. Lithium reacts

leisurely with water. Cesium reacts very violently. Very few of the salts of Group 1







metal weirdness). They both have more than one valence and are both somewhat

common in the earth’s crust.

Group 5 is also split between metals and non-metals. Nitrogen and phosphorusare very definitely non-metals. Both are common in the earth’s crust. In the rare

instances that nitrogen and phosphorus form ions, they form triple negative ions.

Nitride (N-3) and phosphide (P-3) ions are unstable in water, and so are not found in

nature. All of the Group 5 elements have five electrons in the outer shell. For the

smaller elements it is easier to complete the shell to become stable, so they are non-

metals.

Group VII (6 or 16) elements, oxygen, sulfur, selenium, and tellurium, have six

electrons in the outside shell. We are not concerned with polonium as a Group 6

element. It is too rare, too radioactive, and too dangerous for us to even consider in a

basic course. Tellurium is the only element in Group 6 that is a semi-metal. There

are positive and negative ions of Tellurium. Oxygen, sulfur, and selenium are true

non-metals. They have a valence of negative two as an ion, but they also bond

covalently. Oxygen gas makes covalent double-bonded diatomic molecules. Oxygen

and sulfur are common elements. Selenium has a property that may be from semi-

metal weirdness; it conducts electricity much better when light is shining on it.

Selenium is used in photocells for this property.

On some charts you will see hydrogen above fluorine in Group VII (7 or 17).

Hydrogen does not belong there any more than it belongs above Group 1. Fluorine,

chlorine, bromine, and iodine make up Group 7, the halogens. We can forget aboutastatine. It is too rare and radioactive to warrant any consideration here. Halogens

have a valence of negative one when they make ions because they have seven

electrons in the outer shell. They are all diatomic gases as free elements near room

temperature. They are choking poisonous gases. Fluorine and chlorine are yellow-

green, bromine is reddish, and iodine is purple as a gas. All can be found attached to

organic molecules. Chlorine is common in the earth’s crust. Fluorine is the most

active of them, and the activity decreases as the size of the halogen increases.

Questions:

1. How was the periodic table formed?

2. How is the table organized?





3. What information can we know when looking at the periodic table?





UNIT SIX : MOLECULESAlthough they are made up of atoms, molecules are still considered one of the

basic units of matter. That is because a molecule is the smallest particle into which a

substance can be divided and still have the chemical identity of the original

substance. If the substance were divided further, only atoms of chemical elements

would remain. For example, a drop of water contains billions of water molecules. If

one water molecule were separated from the rest, it would still behave like water.

But if that water molecule were divided, only atoms of the elements hydrogen and

oxygen would remain.

THE STRUCTURE OF MOLECULESMolecules are made up of atoms held together in certain arrangements. The

forces that hold the atoms of a molecule together are called chemical bonds. Atoms bond by sharing electrons - some atoms give up electrons, some take on electrons,

and in some bonds the electrons orbit the nucleus of two atoms.

Each atom in a molecule consists of a positively charged nucleus surrounded by

negatively charged electrons. When atoms bond, these charges balance each other,

forming an electrically neutral molecule. In some molecules, positive and negative

charges are spread evenly throughout it. In polar molecules, however, more positive

charge collects at one place in the molecule and more negative charge collects at

another place. Some polar molecules are magnetic because of the way the electrons

are unevenly distributed within the molecule.Scientists show the composition of molecules by using the symbols for elements

in chemical formulas. For example, a water molecule consists of two hydrogen

atoms and one oxygen atom. Therefore, the chemical formula for water is written as

H2O.

Molecules are measured by their molecular mass, which equals all the atomic

masses of the atoms in a molecule. The molecular mass of carbon dioxide (CO2) can

be found by adding the atomic mass of one atom of carbon, which is 12, and the

masses of the 2 oxygen atoms, which are about 16 each. The molecular mass of

carbon dioxide, therefore, is about 44.

I. Vocabulary in Context

Chemical bonds - Molecular mass - electrons - polar molecules -

water molecule - nucleus - Molecules - atoms - symbols -

chemical identity - atoms - balance

1. ……………….are considered one of the basic unit of matter

2. A molecule is the smallest particle into which a substance can be divided and

still have the …………………….of the original substance.





3. If we continue to divide molecules, only ……………….would remain.

4. A………………..has the same chemical identity as water we fins

everywhere.

5. Molecules are made up of …………held together in a certain arrangement.

6. …………………….are forces that hold the atoms of a molecule together.

7. We find in each atom of a molecule positively charged ……………

surrounded by negatively charged ……………….

8. Normally, the charges (positive and negative) in a molecule ………….each

other.

9. Electrons are unevenly distributed in ……………………..

10. Scientists use the …………..for elements to show the composition of

molecules in chemical formulas.

11. ………………..equals all the atomic masses of the atom in a molecule.

II. Comprehension questions1. Why do we say that molecules are the basic unit of matter? ………………

…………………………………………………………………………………

2. Can a molecule of water behave chemically as water does? Why? ………..

………………………………………………………………………………..

3. What kinds of charge are there in an atom? …………………………………

…………………………………………………………………………………

4. What does ‘polar molecule’ mean? ………………………………………….

…………………………………………………………………………………

5. How do we show the composition of molecules? …………………………..

………………………………………………………………………………

III. Grammar

A. Both … and:Example: + Inorganic Chemistry is an important branch of chemistry

+ Organic Chemistry is an important branch of chemistry

=> Both Inorganic Chemistry and Organic Chemistry are

important branches of chemistry

+ Atoms can lose electrons.

+Atoms can gain electrons

=> Atoms can both lose and gain electrons











5. If you cook you meal at home and don’t go out too often, you can live ……..

You don’t have to spend too much money.











4. If we want to understand chemistry we must possess an understanding of

elementary particles – atoms and molecules (Rewrite, using so that)

…………………………………………………………………………………………………………………………………………………………………..

5. The atom could collapse in on itself because opposite charges in the atom

attract each other. (because of)

…………………………………………………………………………………

………………………………………………………………………………..

Further exercises

A. COMPLETE THE SENTENCES WITH EITHER BECAUSE,

DUE TO OR BECAUSE OF 1. We postponed our trip ………………….the bad driving conditions.

2. Sue’s eyes were red ……………………she had been swimming in a

chlorinated pool.

3. We cannot visit the museum tomorrow ……………….it’s not open.

4. Tom had to give up jogging ……………………..his sprained ankle.

5. …………………heavy fog at the airport, we had to stay in Dalat an

extra day.

6. ……………………..the elevator was broken, we had to walk up six

flights of stairs.

7. Please walk carefully …………………….the walkway is slippery

when wet.

8. Thousands of Irish people immigrated to the U.S. ……………..the

potato famine in Ireland in the middle of the nineteenth century.

9. The young couple decided not to buy the house ………………..of its

dilapidated3 condition.

10. You cannot enter this secured area …………………you don’t have an

official permit.

B. Complete the sentences with your own words

3 Oïp eïp, hö hoûng





Example: Sam took a lot of pictures on his vacation so (that) ……………

=> Sam took a lot of pictures on his vacation so (that) he could

show his family where he had been

1. I need a pen so (that) …………………………………………………

2. ……………………………………………………………………so

(that) he can improve his English.

3. I turned on the TV so (that) ………………………………………..

4. I am taking a bus instead of flying so (that) ………………………..

……………………………………………………………………….

5. I am trying to improve my English so (that) …………………………..

………………………………………………………………………….

6. I will go to HCM City after I graduate from university so (that) ……

…………………………………………………………………………

7. It is necessary for you to study hard so (that) …………………………

………………………………………………………………………….

8. She left early so (that) ………………………………………………..

………………………………………………………………………..

9. We should get up a bit early tomorrow so (that) ……………………..

…………………………………………………………………………

10. ………………………………………………………………..so that

read updated information in my major from the Internet.

C. Choose all correct answer for each sentence

1. A small fish needs camouflage4 to hide …………….its enemies cannot find it.

a. so that b. so c. therefore d. due to

2. John couldn’t open the door ……………….the lock was broken

4 Nguïy trang





a. because b. therefore c. due to the fact that d. so

3. The workers have gone on strike. __________, all production has ceased.

a. Because b. Therefore c. consequently d. Inasmuch as

4.………………….my company’s bid for building the library was the lowest,

we were awarded the contract.

a. Because b. Since c. For d. Inasmuch as

5. I needed to finish the marathon race ………………I could prove that I had the

strength and stamina5 to do it. I didn’t care whether I won or not.

a. because of b. so that c. for d. therefore

6. Let’s ask our teacher how to solve this problem…………………we cannotagree on the answer.

a. since b. because of c. consequently d. as long as

7. Our apartment building has had two robberies in the last month, …………I’m

going to put an extra lock on the door and install a telephone in my bedroom.

a. now that b. so that c. so d. since

8. ……………………the bad grease stain on the carpet, we had to rearrange the

furniture before the company arrived.

a. Because of b. Now that c. Due to d. Since

9. The price of airline tickets has gone down recently. ……………the tickets

cost less, more people are flying than ever.

a. Consequently b. Because of c. Because d. For

10. The mountain road was closed to all traffic………………the heavy rainfall

had caused a hug mudslide that blocked the way.

a. therefore b. because c. due to d. so

11. Janet called the security guard……………..someone had taken her brief

while she was making a call at the public phone.a. so that b. so c. because d. because of

12. Dolphins are sometimes caught and killed in commercial fishing nets

………..they often swim in school with other fish, such as tuna.

a. since b. as c. so d. because

WORD STUDY

5 Söùc chòu ñöïng, söï deûo dai





Suffixes: You can change some words into verbs by adding the suffix –ize. The

suffix –ize means ‘to make into (something)” or “to cause to be (something).”

Here is an example: Radio helps to popularize country music

Popular + ize = to make something (country music) popular

When a word ending in –y, drop the y before adding –ize

Add the suffix –ize to each word. Then choose the best word for each sentence.

Be sure to use the correct tense

Memory ……………………… Special ………………………….

Winter ……………………….. Modern …………………………

Colon ………………………… Industrial ………………………

Colony ………………………

1. Spain and Portugal started many new cities in the New World, especially in

South Mexico. These countries ………………..most of Central and South

America.

2. The Greens bought a beautiful old house in the country. They

……………….the kitchen by adding a dishwasher, a micro wave, and a new

refrigerator. The rest of the house is not modern. It has simple furniture and old

wood floors, but it’s very nice.

3. Victor is studying engineering at the university. After two years of general

studies, he wants to …………………….in biomedical engineering.

4. Sometimes there are no rules for irregular verbs in English. If you want to

remember them, you have to ………………them and use them often.

5. Every fall I take my car to the auto mechanic. He changes the oil and adds

some chemicals to help it run well during the winter. He thinks all people should

……… their car to prevent problems during the very cold months.

6. Developing countries want to ……………..……..as fast as possible. They

want to change from a society of farm workers to a society of modern factory

workers. Having a strong industry will help these countries grow.









UNIT EIGHT: GASES, LIQUIDS AND SOLIDSGases

Gas, or vapor, is the most energetic phase of matter commonly found here on

earth. The particles of gas, either atoms or molecules, have too much energy to settle

down attached to each other or to come close to other particles to be attracted by

them. Materials in the vapor phase have no shape of their own, that is, they take on

the shape of the container. Gases have no given volume. A certain amount of gas at

a pressure of one atmosphere and a volume of ten liters could become five liters if

the pressure was increased or would become more than ten liters if the pressure

were decreased. The gas expands to fill the container.

How can you picture the materials as a gas? A pool table is only in two

dimensions, but what if the balls kept moving and the pool table were in three

dimensions? Such a pool table would be like a gas. The rails of the 3-D pool table

would be the sides of the container. The billiard balls would bounce off each other

in completely elastic collisions and would bounce off the sides of the table to

produce a constant pressure. The real hallmark of the gas is that the motion of the

particles is so great that the forces of attraction between the particles are not able to

hold any of them together.

LiquidsLiquids are materials in which the atoms or molecules are as close to each other

as solids, but the materials can slip over each other to change places.

The property of liquids of incompressibility is useful to us in hydraulic

machines.

Solids

Solids are materials in which the atoms or molecules are set in place. In ionic

solids such as table salt crystals, the ions are connected to their neighbors by

electrical attraction. Covalently linked crystals such as diamonds produce the

hardest materials. In other solids, each unit may have its own spot in which it fits (as

in sugar crystals) or it may be just a jumble of molecules as in glass that have

decreased energy. Crystalline solids have characteristic angles and can be cleaved

along lines defined by the aligning of atoms or molecules of the crystal. Amorphous

(without crystal shape) solids can be like carbon black or linked as in plastics. The

common point about solids is that the atoms or molecules are in place. The

temperature that can be shown by solid materials is due to the movement in place of

the atoms or molecules. They have no independent linear motion of translation





because they are attached to one another. Solids can have molecular energy due to

vibration and rotation. Picture a class of second graders glued to their seat. Each

student can jump up and down and sideways and turn the chair around, but theycan’t move out of place. Another useful mental picture is a junkyard for springs.

The springs have all been tied to each other in one enormous mass. Each spring can

twist and vibrate, but it can’t get loose from its neighbor.

It is now necessary to change from being able to see and understand each atom

or molecule to our larger world. Solids show a definite shape and a definite volume.

Unless forces are used that are not commonly found near the earth’s surface, solids

cannot be compressed.

I. Vocabulary in context

Gases

forces of attraction - motion - attract - energetic - volume

1. The particles of gases either atoms or molecules, are very ……………..

2. Particles of gases, atoms or molecules, do not ………….each other as those

of other substances like solid or liquid.

3. The ………………of gas is not stable; it can be increases or decreased

depending on different conditions.

4. The ………………of gas particles is high.

5. The ………………………….between gas particles are not strong enough to

hold them together.

Liquids

greater - slip over

1. Atoms or molecules of liquids are able to ……………..each other to change places.

2. The forces that hold particles of liquid are …………..than the forces caused

by the motion of those particles.

Solids







6. Do solids have shape? -----------------------------------------------------------

7. What is special about crystalline solids?

--------------------------------------------------------------------------------------------

8. Can particles of solids move around? Why?

--------------------------------------------------------------------------------------------

9. Can we compress solid? How?

--------------------------------------------------------------------------------------------

III. Grammar: Verb + ing Structure

• Gerund: Gerunds functions as a noun standing alone, or operate as a verb in

a phrase

Example: + Smoking is a bad habit

+ I like swimming

+ He left the house, knowing that it was the last time he saw it

• Participle: Present participles function as an adjective, or as a verb in a phrase

Example: + Electrons spin around the nucleus at such amazing speed

that they create the effect of a rigid exterior.

+ Each electron shell is designated by a number-the shell

closest to the nucleus is called shell 1, and the others are called

2, 3, 4, 5, 6, and 7, in order of their increasing distance from

the nucleus

1. Qualitative Analysis provides methods of (finding) ……………. outwhether a given sample of matter contains lead or gold.

2. The chemistry of carbon compounds is called Organic Chemistry; the

(remain) ………………… is called Inorganic Chemistry.

3. Electrons occupy almost me entire volume of an atom, (travel)…....

through the space around the nucleus, and (complete)………. billions

of trips each millionth of a second.









SO YOU WANT TO BE A LIQUID

If you want to be a liquid you could start out as twodifferent things. You could be a solid or you could be a gas.

Each of them has a different way of becoming a liquid.

Let's say you're a solid. That's you. A handsome cube of ice

sitting on a counter. All you do is dream of becoming liquid

water. What you need is some energy. Atoms in a liquid have

more energy than the atoms in a solid. The easiest energy

around is probably heat. There is a magic temperature for

every substance called the melting point. When a solid reaches

the temperature of its melting point... It can become a liquid.For water the temperature has to be a little over zero degrees

Celsius. If you were salt, sugar or wood your melting point

would be higher than water.

So solids need more energy. The reverse is true if you are a

gas. You need to lose some energy from your very excited gas atoms. The easy

answer is to lower the surrounding temperature. When the temperature drops,

energy will be sucked out of your gas atoms. When you get to the condensation

point, that's the temperature when you become a liquid. If you were the steam of a

boiling pot of water and you hit the wall, the wall would be so cool that you would

quickly become a liquid.

Evaporation

Sometimes a liquid can be sitting there and its molecules

will become a gas. That's called EVAPORATION. You

might be wondering how that can happen when the

temperature is low. It turns out that all liquids can

evaporate at room temperature and pressure. Evaporation is

when there are atoms or molecules escaping from the liquid

and turning into a vapor. You see... Not all of the

molecules in a liquid actually have the same energy. The

energy you can measure is really an AVERAGE of all the

molecules. There are always a few molecules with a lot of

energy and some with barely any energy at all. It is those

with a lot of energy that build up enough power to become a

gas and leave the liquid. When it leaves it has evaporated.





SOLID BASICS

Solids can be made up of many things. They can have elements or compoundsinside. They can also be made up of mixtures, or combinations of differentelements and compounds. Most of the solids you see are mixtures. Most rocks

are mixtures of many elements and compounds. Concrete is a good example of a

man-made solid mixture.

Characteristics Of Solids

First let's explain that characteristicsare the traits or features that something

might have. One characteristic of a solidis that it might be hard. That idea is

pretty straight forward.

One of the main characteristics ofsolids is that they hold their own shape. So if you put a solid in a container it

won't change its shape... No matter how much you move or slide it around. You

can even grind a solid up so that it fills up a container. If you look at the powderunder a microscope you will still see little tiny solids that you couldn't change.

You know that liquids are different because if you put a liquid into a container it

will fill it up as much of the container as it can.

In the same way that a solid holds its shape the atoms inside of a solid are not

allowed to move around much. This is a physical characteristic

of all solids. It happens no matter how small the pieces are. The

atoms in liquids and gases move around in all directions. Thesolid atoms and molecules are trapped in their places. The

atoms still spin and the electrons still move but the entire atomdoesn't go anywhere. They just kind of jiggle in place.

So You Want To Be A Solid

Obviously not everything is a solid. If you look around you'll see solids,

liquids, and especially gases (remember the air around you). Sometimes liquidsfeel a physical need to become a solid. Then look out! Phase changes are about to

happen.







UNIT NINE: A COMPOUND'S IDENTITYA compound is a substance that is made up of at least two different elements

and, therefore, two different kinds of atoms. Compounds are distinctive in that they

always have the same composition by weight. No matter what part or how much of

a compound you isolate, it will always have the same ratio between elements that

the original compound has. Water, for example, is a compound that consists of

molecules that have one atom of oxygen and two atoms of hydrogen. Therefore, in

any sample of water, there will always be twice as many hydrogen atoms as oxygen

atoms.

Every compound can be described by a particular chemical formula, which

shows the ratio between the elements that make up the compound. Chemists write

formulas using the symbols for chemical elements. Chemical formulas show themakeup of one unit of a compound; these units generally occur as molecules or ions.

The composition of simple molecules can be shown in a formula by combining

the symbols for the elements that the compound contains. Hydrogen fluoride, for

instance, is made up of molecules that contain one atom of hydrogen and one atom

of fluorine. Its formula can be written as HF.

Many molecules have more than one atom of the same element. Formulas for

these molecules include numbers written just below the symbols as subscripts. The

subscripts indicate the number of atoms included in a molecule. For example.

carbon dioxide is a compound that contains one carbon (C) atom and two oxygen(O) atoms. The formula for carbon dioxide is written CO2.

Formulas for compounds that consist of ions show the symbols of elements

whose atoms exist as ions in the compound. The compound sodium chloride, or

common table salt, has equal amounts of sodium (Na) and chlorine (Ct) atoms that

occur as ions. The formula for sodium chloride is written NaCl.

HOW COMPOUNDS ARE FORMEDA compound is formed when atoms of one element bond with atoms of another

element. Atoms tend to bond as a means of becoming more stable. A stable atom is

one that has the maximum amount of electrons in its outer shell. Therefore, atoms bond through the exchange of electrons, which are either transferred from one atom

to another or shared by more than one atom.

The capacity of an atom to combine with another atom is referred to as its

valence. Atoms of an element are assigned a valence number, which generally

equals the number of electrons that an atom needs to fill or release from its

outermost shell. Atoms that tend to lose electrons have a positive valence, and those

that tend to gain electrons have a negative valence. However, an atom of a certain

element may combine in a number of different ways with different elements. Thus,





an atom may be assigned more than one valance number, depending on the number

of different bonds it tends to form.

I. Vocabulary in Context negative valance - makeup - ratio - Valance - compound - positive valance -

Elements - subscripts - symbols - Chemical formulas -electrons -

atoms - ratio - atom – stable - equals - more than one

1. In a compound, there are at least two different ………………., and therefore,

two different kinds of …………………….

2. No matter how much of a compound we separate, it always contain the same

…………………between the elements that the original compound has.

3. ……………………………are used to describe compounds.

4. A chemical formulas tells us the ………………between the elements that

make up the compound.

5. Chemical formulas are represented by …………………….

6. Each chemical formula shows the ……………….of one unit of a compound

which generally occurs as a molecules or an ion.

7. In many molecules, there is more than one ………………of the same

element.

8. To show formulas for molecules in which there are more than one atom of

the same element, scientists use numbers as ……………….which is written

just below the symbols.

9. When atoms of one element bond with atoms of another element, a

……………….is formed.

10. An atom that has the maximum amount of electrons is the outer shell is saidto be …………………..

11. When atoms bond, they transfer ……………..from one atom to another, or

share the electrons.

12. …………………is a word used to refer to the capacity of an atom to

combine with another atom.





13. The valance number generally ………………the number of electrons that

an atom needs to fill or release from its outermost. Shell.

14. Atoms that tend to lose electrons have a ………………………., and atoms

that tend to gain electrons have a …………………….

15. One atom may be assigned ………………………valance.

II. Comprehension questions

1. What is a compound? ………………………………………………….

……………………………………………………………………….

2.

What does the phrase “compound always have the same composition byweight” mean? ………………………………………………………

…………………………………………………………………………..

3. What can we know by looking at the chemical formula of a compound?

………………………………………………………………

…………………………………………………………………………..

4. How do we represent a compound / a molecule in which there are more

than one atom of the same element? ……………………………

…………………………………………………………………………

5. What happens when atoms of one element bond with atoms of another

element? ………………………………………………………………..

…………………………………………………………………………..

6. Why do atoms have the tendency of bonding with others? …………..

…………………………………………………………………………..

7. What is a stable atom? ………………………………………………….

…………………………………………………………………………..

8. In what ways can atoms bond? ………………………………………..

………………………………………………………………………….

9. What does ‘valance’ mean? …………………………………………..

………………………………………………………………………….

10. What kind of valance an atom has when it gains electrons? And when it

loses electrons? ……………………………………………………….

……………………………………………………………………………

………………………………………………………………………





III. Review on vocabulary:

decomposed - Atomic number - Isotopes - chemical element - Electrons - Mass compound - number - Compounds – atoms - broken - scientific study

1. Matter consists of chemical elements in pure form and in

combinations called ……………………….

2. A ……………………….is a substance that cannot be broken down

into other substances by chemical reactions.

3. ………………………is number of protons in an atom of a particular

element

4. ……………………..is number of protons and neutrons in an atom.

5. …………………..is used to refer to atoms of an element that have the

same atomic number but different mass numbers.

6. …………………….are the only subatomic particles that participate in

chemical reactions.

7. All matter is made of ………………., the smallest bit of each element.

A particle of a gas could be an atom or a group of atoms.

8. Chemical elements are substances that cannot be ……………..or

…………………..into more simple substances by ordinary chemical

means.

9. Most substances are ……………………, in that they are composed of

combinations of atoms.

10. Chemistry is the …………………….of the substances that make up

the universe.

IV. Grammar – Preposition

Prepositions are words normally placed before nouns or pronouns.

Prepositions can also be followed by verbs but the verbs should be in Gerund

form.

Example: Analytical Chemistry is the experimental foundation of

chemistry.







FURTHER EXERCISES

INSERT AN APPROPRIATE PREPOSITION INTO THE BLANK1. Could I speak …………. John, please?

I’m afraid, john is ………..work.

2. How do I get …………..the air terminal?

Turn right ……………..the end of this street and you’ll see it ………

front of you.

3. He started going ………………school ……………..the age of five.

4. I’m going ……………Ha Long …………….Monday ………….Tom. wouldyou like to come ………….us?

5. The car stopped ……………..the traffic lights and wouldn’t start again, so

the driver got ………………..and pushed it ……………the side ………..the

road.

6. Children get gifts …………….Christmas and …………………their

birthday.

7. As she was getting ………….the car, one …………..her buttons fell………

Although we were …………..a hurry, she insisted ……………..stopping tolook for it.

8. The man ………….the pipe and red hair is the brother ………..the girl

……... blue.

9. I buy a newspaper ………………my way ………………the station and read

it ……………the train. By the time I get …………London I’ve read most

…… it.

10. He was in charge ………….driving.

11. I’ve lived ………………this street ………………….ten years.

12. …………….the age ……………18 he was sent to prison ………..theft.

13. There is a parcel …………..books …………..you ……….the table ……….

the hall.

14. While ……… their way from the coast ……………the mountains they were

attacked …………….a jaguar.





15. He has a picture ………..Picasso ( picture painted by Picasso) and he cannot

decide whether to hang it …………….the hall………….the right as you

come or ………………the sitting room …………..the fireplace.

16. He insisted …………..seeing the documents.

17. I am not interested ……………….anything that happened ………..the very

remote past.

18. They succeeded ……………..escaping ………….the burning house.

19. I’m waiting ……………….my friend. He’ll be here ……………a moment.

20. I was so afraid………………missing the train that I took a taxi……………the station.

21. I object …………..being kept waiting. Why can’t you be …………………..

time?

22. Wine is good …………..you, but it is expensive …………….England

because there is a fairly high tax ………………it.





UNIT TEN: IONIC AND COVALENT BONDS

Ionic bonds are created by the transfer of electrons from one atom to one or more

other atoms. The atoms that looses electrons become positive ions. The atoms that

gain electrons become negative ions. The force that holds ionic compounds together

is called an ionic bond.

Some atoms, such as metals tend to lose electrons to make the outside ring or

rings of electrons more stable and other atoms tend to gain electrons to complete the

outside ring. An ion is a charged particle. Electrons are negative. The negative

charge of the electrons can be offset by the positive charge of the protons, but the

number of protons does not change in a chemical reaction. When an atom loses

electrons, it becomes a positive ion because the number of protons exceeds the

number of electrons. Non-metal ions and most of the polyatomic ions have a

negative charge. The non-metal ions tend to gain electrons to fill out the outer shell.

When the number of electrons exceeds the number of protons, the ion is negative.

The attraction between a positive ion and a negative ion is an ionic bond. Any

positive ion will bond with any negative ion. They are not fussy. An ionic

compound is a group of atoms attached by an ionic bond that is a major unifying

portion of the compound. A positive ion, whether it is a single atom or a group of

atoms all with the same charge, is called a cation. A negative ion is called an anion.

The name of an ionic compound is the name of the positive ion (cation) first and the

negative (anion) ion second.

Table salt, properly called sodium chloride (NaCl), is an ionic compound. Salt is

formed when a sodium atom gives up an electron to a chlorine atom. The sodium

atom which loses the negative electric charge that the electron carries, becomes a

positive ion. The chlorine atom gains the negative charge, and becomes a negative

ion. Opposite charges attract, and so the two atoms are joined in an ionic bond.

COVALENT BONDS are formed when two or more atoms share pairs of

electrons. A shared pair consists of one electron from each of two atoms. These

electrons revolve around the nucleus of both atoms. Covalent bonds form molecules,

which ordinarily have no electrical charge. Compounds that consist of molecules

can be called covalent compounds.

Water is an example of a common compound. It is an example of a covalent

compound. It is made up of hydrogen and oxygen atoms. The outer shell of an

oxygen atom requires two additional atoms to become stable. Hydrogen atoms have

one electron, but need another to fill the outer shell. So when two hydrogen atoms

combine with one oxygen atom, all the vacancies are filled, forming a molecule of

water.





Nearly all elements in their natural states are joined by covalent bonds.

Hydrogen, for example, normally consists of covalently bonded molecules. An

ordinary hydrogen molecule (H2) has two atoms that share electrons, so that twoelectrons revolve around each nucleus. Covalent compounds are often joined by

bonds that are much more complicated. Some individual molecules are held together

by many different covalent bonds.

I. Vocabulary in Context

ionic compound - anion - revolve - positive ion - covalent bonds -

covalent bonds - ionic bonds - ionic bond - cation

1. When electrons are transferred from one atom to one or more other

atoms, …………..are created.

2. An ion will become a ……………….when it loses electrons.

3. An ion will become a ………………when it gains electrons.

4. An ……………….is one that holds ionic compounds together.

5. An …………..is a group of atoms attached by an ionic bond that is a

major unifying portion of the compound.

6. A positive ion is called a …………….

7. A negative ion is called an ……………..

8. When two or more atoms share pairs of electrons, they form …………

……….

9. Electrons in the shared pairs ……………around the nucleus of both

atoms.

10. Most element in their natural states are joined by ………………..

II. Vocabulary in new context:

ionic bond - Covalent bonds

1. An ……………is one formed by electrostatic attraction after the

complete transfer of an electron from a donor atom to an acceptor

atom.





2. ……………..occur between atoms, and are formed by equal sharing

of electrons between atoms.

III. Comprehension Question1. Why do some atoms tend to gain or lose electrons? ……………………....

……………………………………………………………………………..

2. Why does an atom become a positive ion when it loses electrons? ………..

…………………………………………………………………………….

3. Why do non-metal ions tend to gain electrons? …………………………..

………………………………………………………………………………

4. What is an ionic bond? ……………………………………………………

……………………………………………………………………………….

5. When are ionic bonds formed? …………………………………………….

……………………………………………………………………………….

6. What are covalent bonds? ………………………………………………….

………………………………………………………………………………

7. What is a ‘share pair’? ……………………………………………………..

………………………………………………………………………………

8. What kind of chemical bond is more common, ionic or covalent? …………

……………………………………………………………………………….

GRAMMAR: Preposition (Cont.)

Insert an appropriate preposition

1. GASEOUS SOLUTIONS result ………….. the mixture of gases.

2. Additional energy in the electrons keeps them spinning around, which prevents the atom …………… collapsing.

3. Water, for example, is a compound that consists ………… molecules that

have one atom of oxygen and two atoms of hydrogen.

4. Gas, or vapor, is the most energetic phase …….. matter commonly found

here on earth.

5. Gases and solids that dissolve ………… liquid are described as soluble.









………………………………………………………………………………

g. That’s the house. I was born in it.

………………………………………………………………………………

h. Where is the lady? She ordered the fish.

………………………………………………………………………………

i. Do you know the children? They live in that house.

………………………………………………………………………………

j. The clothes come from Marks & Spencer. They are good quality.

……………………………………………………………………………… Further readings

STRUCTURE AND BONDING

1. Why do atoms bond together?

Some atoms are very reluctant to combine with other atoms and exist in

the air around us as single atoms. These are the Noble Gases and have very stable

electron arrangements eg 2, 2.8 and 2.8.8 and are shown in the diagrams below.

(atomic number) and electron

arrangement.

All other atoms therefore, bond to become electronically more stable, that is to become like Noble Gases in electron arrangement. Atoms can do this in two ways:

COVALENT BONDING - sharing electrons to form molecules with covalent

bonds, the bond is usually formed between two non-metallic elements in a

molecule.

OR





IONIC BONDING - By one atom transferring electrons to another atom. The

atom losing electrons forms a positive ion and is usually a metal. The atom

gaining electrons forms a negative ion and is usually a non-metallic element.

The types of bonding and the resulting properties of the elements or compounds are

described in detail below. In all the electronic diagrams ONLY the outer

electrons are shown.

2. Covalent Bonding

Covalent bonds are formed by atoms sharing electrons to form

molecules. This type of bond usually formed between two non-metallic

elements. The molecules might be that of an element ie one type of atom only OR

from different elements chemically combined to form a compound.

The covalent bonding is caused by the mutual electrical attraction between the two

positive nuclei of the two atoms of the bond, and the electrons between them.

One single covalent bond is a sharing of 1 pair of electrons, two pairs of shared

electrons between the same two atoms gives a double bond and it is possible for two

atoms to share 3 pairs of electrons and give a triple bond.

The bonding in Small Covalent Molecules

The simplest molecules are formed from two atoms and examples of their formation

are shown below. The electrons are shown as dots and crosses to indicate which

atom the electrons come from, though all electrons are the same. The diagrams may

only show the outer electron arrangements for atoms that use two or more electron

shells. Examples of simple covalent molecules are …

Example 1

2 hydrogen atoms (1) form the molecule of the element hydrogen H2

and combine to form where both atoms have a pseudo

helium structure of 2 outer electrons around each atom.

Example 2

2 chlorine atoms (2.8.7) form the molecule of the element chlorine Cl2





and combine to form where both atoms have a

pseudo neon or argon structure of 8 outer electrons around each atom.

Example 3

1 atom of hydrogen (1) combines with 1 atom of chlorine (2.8.7) to form the

molecule of the compound hydrogen chloride HCl

and combine to form where hydrogen is

electronically like helium and chlorine like neon or argon.

Example 4

2 atoms of hydrogen (1) combine with 1 atom of oxygen (2.6) to form the molecule

of the compound we call water H2O

and and combine to form so that the hydrogen

atoms are electronically like helium and the oxygen atom becomes like neon or

argon. The molecule can be shown as with two hydrogen - oxygen single

covalent bonds.

Example 5

3 atoms of hydrogen (1) combine with 1 atom of nitrogen (2.5) to form the molecule

of the compound we call ammonia NH3





three of and one combine to form so that the

hydrogen atoms are electronically like helium and the nitrogen atom becomes like

neon or argon. The molecule can be shown as with three nitrogen -

hydrogen single covalent bonds.

Example 6

4 atoms of hydrogen (1) combine with 1 atom of carbon (2.4) to form the molecule

of the compound we call methane CH4

four of and one of combine to form so that the

hydrogen atoms are electronically like helium and the nitrogen atom becomes like

neon or argon. The molecule can be shown as with four carbon -


All the bonds in the above examples are single covalent bonds. Below are three

examples 7-9, where there is a double bond in the molecule, in order that the atomshave stable Noble Gas outer electron arrangements around each atom.

Example 7

Two atoms of oxygen (2.6) combine to form the molecules of the

element oxygen O2. The molecule has one double covalent bond .





Example 8

One atom of carbon (2.4) combines with two atoms of

oxygen (2.6) to form carbon dioxide CO2. The molecule can be shown as

with two carbon = oxygen double covalent bonds.

Example 9

Two atoms of carbon (2.4) combine with four atoms of

hydrogen (1) to form ethene C2H4. The molecule can be shown as

with one carbon = carbon double bond and four carbon -


The Properties of small covalent molecules

The electrical forces of attraction between atoms

in a molecule are strong and most molecules do

not change on heating. However the forces

between molecules are weak and easily

weakened further on heating. Consequently smallcovalent molecules have low melting and

boiling points. They are also poor conductors

of electricity because there are no free electrons

or ions in any state to carry electric charge. Most

small molecules will dissolve in a solvent to f

a solution.

orm

ropertiesLarge Covalent Molecules and their P





It is possible for many atoms to link up to form a giant covalent structure. This

produces a very strong 3-dimensional covalent bond network. This illustrated by

carbon in the form of diamond. Carbon can form four single bonds to four otheratoms etc. etc. This type of structure is thermally very stable and they have high

melting and boiling points. They are usually poor conductors of electricity

because the electrons are not usually free to move as they can in metallic structures.

Also because of the strength of the bonding in the structure they are often very hard

and will not dissolve in solvents like water.

3. Ionic Bonding

Ionic bonds are formed by one atom transferring electrons to another atom to

form ions. Ions are atoms, or groups of atoms, which have lost or gained electrons.

The atom losing electrons forms a positive ion (a cation) and is usually a metal.

The overall charge on the ion is positive due to excess positive nuclear charge

(protons do NOT change in chemical reactions).

The atom gaining electrons forms a negative ion (an anion) and is usually a non-

metallic element. The overall charge on the ion is negative because of the gain, and

therefore excess, of negative electrons.

The examples below combining a metal from Groups 1 (Alkali Metals), 2 or 3, with

a non-metal from Group 6 or Group 7 (The Halogens)

Example 1

A Group 1 metal + a Group 7 non-metal eg sodium + chlorine è sodium chlorideNaCl or ionic formula Na

+Cl

-

In terms of electron arrangement, the sodium donates its outer electron to a chlorine

atom forming a single positive sodium ion and a single negative chloride ion. The

atoms have become stable ions, because electronically, sodium becomes like neon

and chlorine like argon.

Na (2.8.1) + Cl (2.8.7) è Na+ (2.8) Cl

- (2.8.8)





ONE combines with ONE to form

Example 2

A Group 2 metal + a Group 7 non-metal eg magnesium + chlorine è magnesium

chloride MgCl2 or ionic formula Mg2+

(Cl-)2

In terms of electron arrangement, the magnesium donates its two outer electrons to

two chlorine atoms forming a double positive magnesium ion and two single

negative chloride ions. The atoms have become stable ions, because electronically,

magnesium becomes like neon and chlorine like argon.

Mg (2.8.2) + 2Cl (2.8.7) è Mg2+

(2.8) 2Cl- (2.8.8)

ONE combines with TWO to form

see *

(* NOTE you can draw two separate chloride ions, but in these examples a number

subscript has been used, as in ordinary chemical formula)

Example 3

A Group 3 metal + a Group 7 non-metal e.g. aluminium + fluorine è aluminium

fluoride AlF3 or ionic formula Al3+

(F-)3

In terms of electron arrangement, the aluminium donates its three outer electrons tothree fluorine atoms forming a triple positive aluminium ion and three single

negative fluoride ions. The atoms have become stable ions, because electronically,

aluminium becomes like neon and also fluorine.

Al (2.8.3) + 3F (2.8.7) è Al3+

(2.8) 3F- (2.8)





ONE combines with THREE to form

Example 4

A Group 1 metal + a Group 6 non-metal eg potassium + oxygen è potassium oxide

K2O or ionic formula (K+)2O

2-

In terms of electron arrangement, the two potassium atoms donates their outer

electrons to one oxygen atom. This results in two single positive potassium ions toone double negative oxide ion. All the ions have the stable electronic structures

2.8.8 (argon like) or 2.8 (neon like)

2K (2.8.8.1) + O (2.6) è 2K+ (2.8.8) O

2- (2.8)

TWO combine with ONE to form

Example 5

A Group 2 metal + a Group 6 non-metal eg calcium + oxygen è calcium oxide CaO

or ionic formula Ca2+

O2-

In terms of electron arrangement, one calcium atom donates its two outer electrons

to one oxygen atom. This results in a double positive calcium ion to one double

negative oxide ion. All the ions have the stable electronic structures 2.8.8 (argonlike) or 2.8 (neon like)

Ca (2.8.8.2) + O (2.6) è Ca2+

(2.8.8) O2-

(2.8)

ONE combines with ONE to form





Example 6

A Group 3 metal + a Group 6 non-metal eg aluminium + oxygen è aluminiumoxide Al2O3 or ionic formula (Al3+

)2(O2-

)3

In terms of electron arrangement, two aluminium atoms donate their three outer

electrons to three oxygen atoms. This results in two triple positive aluminium ions

to three double negative oxide ions. All the ions have the stable electronic structure

of neon 2.8

2Al (2.8.3) + 3O (2.6) è 2Al3+

(2.8) 3O2-

(2.8)

TWO combines with THREE to form

The properties of Ionic Compounds

• The ions in an ionic solid are arranged in

an orderly way in a giant ionic lattice shown in

the diagram on the left. The ionic bond is the

strong electrical attraction between the

positive and negative ions next to each other in

the lattice. Salts and metal oxides are typical

ionic compounds.

• This strong bonding force makes the

structure hard (if brittle) and have high melting

and boiling points. Unlike covalent molecules,

ALL ionic compounds are crystalline solids at

room temperature.

• Many ionic compounds are soluble in

water, but not all.

• The solid crystals DO NOT conduct electricity because the ions are not

free to move to carry an electric current. However, if the ionic compound is melted

or dissolved in water, the liquid will now conduct electricity, as the ion particles

are now free.




4. Bonding In Metals

The crystal lattice of metals consists of ions NOT atoms. The outer electrons (-) from the original metal atoms are free to

move around between the positive metal

ions formed (+). These free or 'delocalised'

electrons are the 'electronic glue' holding

the particles together. There is a strong

electrical force of attraction between

these mobile electrons and the 'immobile'

positive metal ions - this is the metallic

bond.

• This strong bonding generally results in dense, strong materials with high

melting and boiling points.

• Metals are good conductors of electricity because these 'free' electrons carry

the charge of an electric current when a potential difference (voltage!) is applied

across a piece of metal.

• Metals are also good conductors of heat. This is also due to the free moving

electrons. Non-metallic solids conduct heat energy by hotter more strongly vibrating

atoms, knocking against cooler less strongly vibrating atoms to pass the particle

kinetic energy on. In metals, as well as this effect, the 'hot' high kinetic energy

electrons move around freely to transfer the particle kinetic energy more efficientlyto 'cooler' atoms.

• Typical metals also have a silvery surface but remember this may be easily

tarnished by corrosive oxidation in air and water.






UNIT ELEVEN: CHEMICAL REACTIONSChemical reactions are constantly carried out in our lives. The digestion of food,

the burning of fuel - even the development of photographic film - all involve

chemical reactions. Understanding and predicting chemical reactions is an important

way in which scientists apply the concepts of chemistry to everyday life.

A chemical reaction is a process in which one substance is chemically converted

into a different substance. In all chemical reactions, bonds between atoms are

broken and new ones are formed. Thus, the molecular or ionic structure of the

substance a chemical reaction creates is always different from the structure of the

original substance.

All the changes we witness, however, are not chemical reactions. There are also

physical changes and nuclear reactions. In a physical change, the substanceundergoing change has the same chemical formula as the resulting substance. The

melting of ice, for example, is a physical change, because the structure of the water

molecules remains the same. In a nuclear reaction, an atom is transformed into

another type of atom as a result of changes in the composition of its nucleus.

A chemical equation is a way to describe what goes on in a chemical reaction, the

actual change in a material.

CHEMICAL EQUATIONS demonstrate what occurs in chemical reactions.

These equations consist of chemical formulas and symbols that describe the

substances that are involved in the reaction. For example, the following is thechemical equation for the rusting of iron:

4Fe(s) + 3O2(g)→ 2Fe2O3(s)

This equation states that four atoms of solid iron (Fe[s]) react with three

molecules of oxygen gas (O2[g]) to form two units of solid rust (Fe2O3[s]).

Experiments that have been performed on this reaction have proven that iron and

oxygen always react in these proportions.

All chemical reactions have at least one product and at least one reactant. In the

rusting of iron, rust is the product , or result, of the reaction. Iron and oxygen are the

reactants, the substances that undergo chemical change.

The Total number of atoms and the kinds of atoms do not change in a chemical

reaction. The number of atoms in the reactants is the same as the number of atoms in

the products. In this way, chemical equations are similar to mathematical equations.

Both sides— of the arrow, in a chemical equation—must balance. Thus, in the

equation for the rusting of iron, the reactants contain a total of 10 atoms: 4 atoms of

iron and 6 atoms of oxygen. Likewise, the product contains 10 atoms. But the

formula of the product is very different from the formulas of the reactants.





I. Vocabulary in context

reactants - symbols - physical change - kind of atoms - chemically - chemical reactions - product - chemical reaction - reactant -

chemical equation - product

1. Most activities in our lives, from the digestion of food to the burning of

fuel, all involve ………………………

2. The process in which one substance is …………….converted into a

different substance is called ……………………….

3. In a ……………………., the material/substance does not have a different

chemical formula after the change.

4. We use …………………………to show what occurs in chemical

reactions.

5. Chemical formulas and …………………are used to describe the substance

that are involved in the reaction.

6. Every chemical reaction has at least one ………………and at least one

……………………...

7. In a chemical reaction, the quantity of atoms and the ………………do not

change.

8. In a chemical reaction, the number of atoms in the ………………and thenumber of atoms in the ………………are equal.

II. Vocabulary in new context

symbols - products - reactants – reactants - chemical equation - arrow -

chemical reaction - chemical reaction - products

1. A ……………………..is material changing from a beginning mass to a

resulting substance.

2. The hallmark of a chemical reaction is that new material or materials aremade, called ………………….., along with the disappearance of the mass

that is changed to make the new, so-called ………………..

3. A …………………is used to describe what goes on in a chemical

reaction, the actual change in a material.

4. Chemical equations are written with the …………..of materials to include

elements, ionic or covalent compounds, aqueous solutions, ions, or

particles.





5. There is an …………….pointing to the right that indicates the action of

the reaction.

6. The materials to the left of the arrow are the ………………, or the

materials that are going to react.

7. The materials to the right of the arrow are the ………………, or the

materials that have been produced by the reaction.

8. The Law of Conservation of Mass states that in a …………………..no

mass is lost or gained.

III. Reading comprehension

1. Write T if the following statement is true and F if false

a. Chemical reactions only happen in laboratory. ----------------

b. Understanding and predicting chemical reactions is necessary.---------

c. In a chemical reaction, new materials are produced. -------------------

d. New bonds between atoms are formed during chemical reactions. -----

e.

The structure of molecules or ions of the products are the same as thatof the reactants. -----------------

2. Answer the questions

f. Give some examples in which chemical reactions occur. …………….

…………………………………………………………………………

g. Are all the changes of materials are chemical reactions? Why? Give

examples. ……………………………………………………………..

………………………………………………………………………..

………………………………………………………………………..

h. What can you say about chemical equations? ……………………….

………………………………………………………………………..

i. What can you say about chemical reactions in terms of products and

reactions? ……………………………………………………………

………………………………………………………………………..

j. Do the number of atoms and the kinds of atoms change in a chemical

reaction? Why? ………………………………………………………..

………………………………………………………………………….





Further reading

Chemical Reactions

Now that we know the how and why of chemical bonding, we can look at some

chemical reactions. Chemical reactions happen all around us: when we light a

match, start a car, eat dinner or walk the dog. A chemical reaction is the pathway by

which two substances bond together. In fact we have already discussed several

chemical reactions. One we have mentioned is the reaction of hydrogen with

oxygen to form water. To write the chemical reaction you would place the reactants

(the substances reacting) on the left with an arrow pointing to the the products (the

substances being formed). Given this information, one might guess that the reaction

to form water is written:

H + O H2O

However there are 2 problems with this chemical reaction. First, because atoms

like to have full valence shells, single H or O atoms are rare (and unhappy)

creatures. As we saw in the previous lesson, both hydrogen and oxygen react with

themselves to form the molecules H2 and O2, respectively. These hydrogen and

oxygen molecules are much more common. Given this correction, one might guess

that the reaction looks like this:

H2 + O2 H2O

But we still have one problem. As written, this equation tells us that 1 hydrogen

molecule (with 2 H atoms) reacts with 1 oxygen molecule (with 2 O atoms) to form

1 water molecule (with 2 H atoms and 1 O atom). In other words, we seem to have

lost 1 O atom along the way! To write a chemical reaction correctly, the number of

atoms on the left side of a chemical equation has to be precisely balanced with the

atoms on the right side of the equation. How does this happen in our example? In

actuality, the O atom that we 'lost' reacts with a 2nd molecule of hydrogen to form a

second molecule of water. The reaction is therefore written:

2H2 + O2 2H2O

In the chemical reaction above, the number in front of the molecule (called a

coefficient) indicates how many molecules participate in the reaction. A simulation

of the reaction can be viewed by clicking below (the atoms are represented as

spheres in the animation: red = hydrogen, blue = oxygen):

In order to write a correct chemical reaction, we must balance all of the atoms

on the left side of the reaction with the atoms on the right side. Let's look at another

http://web.jjay.cuny.edu/5-bonds.htm

http://web.jjay.cuny.edu/5-bonds.htm





example. Natural gas is primarily methane. Methane (CH4) is a molecule in which

4 hydrogen atoms are bonded to one carbon atom. If you have a gas stove, lighting

the stove causes the methane to react with oxygen in the atmosphere to release heatand the atoms recombine to form carbon dioxide and water vapor. The unbalanced

chemical reaction would be: CH4 + O2 CO2 + H2O

Look at the reaction atom by atom. On the left side we find 1 carbon atom, and

1 on the right. There are 4 hydrogen atoms on the left, but only 2 on the right.

Therefore, you know 2 water molecules must be formed. Adding this coeffiecient

we get:

CH4 + O2 CO2 + 2H2O

Now we have to balance the oxygen atoms. On the left you find 2 atoms, on the

right 4 (2 in the CO2 molecule and 1 in each of 2 H2O molecules). Therefore we

need to start with 4 oxygen atoms, or 2 molecules. The balanced equation would

then be:

CH4 + 2O2 CO2 + 2H2O

The Mole and Molecular Weights

Up until this point we have been talking about atoms and molecules. The

problem with this approach is that atoms and molecules are very small things. In a

single drop of water for example, there are trillions and trillions of water molecules.

A reaction between a single molecule of hydrogen and a single molecule of oxygen,

as we discussed above, would be undetectable. Instead of talking about single

molecules in science, we talk about groups of molecules. You can think of it like

buying eggs. You don't go to the store and buy an egg - you buy a dozen.

Contained within that dozen are the individual eggs. Its the same thing when we

talk about molecules. We don't talk about single units, we talk about groups.

But even a dozen molecules is a tiny amount. What we need is a big number - a

huge number! That number is the mole. The mole is the scientific community's

baker's dozen. One mole equals 6.02 x 1023

(also known as Avogadro's number). A

6 followed by 23 zeros. Now that's a pretty big number. But that's all it is, a

number. You can't just have a mole, you have to have a mole of something. A mole

of atoms. A mole of water molecules. A mole of pennies (which would make you

richer than you can imagine). Why the mole? As it turns out, the mole has some

interesting properties. One mole of hydrogen atoms (6.02 x 1023

H atoms) weighs 1

g. From the periodic table we know that an He atoms weighs 4 times as much as an

H atom, so go figure, 1 mole of He atoms weighs 4 g. In fact, one mole of any

http://table/

http://table/





element is equal to the atomic mass of that element (in grams).

Let's think about that for a second. If we know the molar mass of an element,

and we know how many elements make up a specific molecule, then you cancalculate the molar mass of a compound by adding up the atomic weights. Huh?

Take water for example. How much does a mole of water weigh? Well, one mole

of water contains one mole of oxygen atoms and two moles of hydrogen atoms. A

mole of hydrogen weighs 1 g and a mole of oxygen weighs 16 g (look at the atomic

mass in the periodic table). So to calculate the weight of one mole of water:

(2 moles H * 1 g per mole) + (1 mole O * 16 g per mole) = 18 g

One mole of water weighs 18 grams!

The mole is also useful in chemical reactions. Though you can't measure

out an atom of hydrogen, you can measure out a mole. Since the mole is just a

constant number, the coefficients in a balanced chemical reaction give you the molar

proportions of reactants and products. In other words:

2H2 + O2 2H2O

tells us that:

2 H2 molecules react with 1 O2 molecule to form 2 H2O molecules.

It also tells us that:

2 moles of H2 molecules react with 1 mole of O2 molecules to form 2 moles of

H2O molecules.





Conditions Of Chemical Reactions

Some chemical reactions occur spontaneously - that is, when two reactants are

simply placed together. The rusting of iron is a spontaneous reaction. Spontaneousreactions occur only when the products are more chemically stable than are the

reactants. Rust, therefore, is more stable than iron or oxygen.

Many chemical reactions, however, do not occur spontaneously. They require

certain conditions. One of the most common conditions that contributes to chemical

reactions is the presence of heat. Heat, a form of energy, can cause substances to

become more reactive, or less stable. Solid rust, as demonstrated in the equation

shown previously, is fairly stable. But when rust is heated in combination with

certain other materials, it becomes metallic iron. This reaction also reveals an

important chemical principle - most reactions are reversible. In other words,

products can be changed back into reactants.

Chemical reactions proceed at different rates, according to different conditions.

Heal, for example, tends to increase the speed of many chemical reactions. Certain

substances, called catalysts, can also accelerate the speed of a chemical reaction.

The process in which a substance increases the speed of a reaction is called

catalysis.

Unlike reactants, catalysts remain unchanged by chemical reactions. In most

cases, there are several possible sequences of steps by which a reaction occurs.

Catalysts participate in some or all of these steps, creating a chemical pathway along

which the entire reaction can proceed more rapidly. In this way, catalysis can lower

the amount of energy needed to cause a chemical reaction.

An example of catalysis is the effect that nitric oxide (NO) has on the

decomposition of ozone (O3) in the upper atmosphere of the Earth. Ordinarily,

ozone decomposes slowly as oxygen atoms and ozone molecules combine and

produce oxygen molecules (O2). The presence of nitric oxide, however, causes the

oxygen molecules to be created rapidly.

Catalysts are used widely in industry to speed up chemical reactions that would

otherwise take place too slowly. Many useful substances, including gasoline and

ammonia, are created through processes that use catalysts, such as platinum and palladium.





UNIT TWELVE: OXIDATION AND REDUCTIONThere is an extraordinary range of possible chemical reactions, some that take

place naturally every day, and others that must be created in a laboratory. Among

the most common - and important in our day-to-day lives - are two related reactions,

called oxidation and reduction. Many essential processes that take place in plants

and animals depend on a whole series of interdependent oxidation and reduction

reactions.

Originally, the term oxidation referred to any chemical process in which a

substance combines with oxygen. Scientists learned, however, that the type of

reaction they were describing could take place, in some cases, without oxygen.

Today, oxidation refers to any chemical reaction in which a substance loses

electrons. Reduction refers to any reaction in which a substance gains electrons.Since the electrons released during oxidation must be captured by another

substance, oxidation is always accompanied by reduction. This combined transfer of

electrons is often called the redox process. The formation of water is an example of

the redox process. Water molecules are formed when oxygen and hydrogen gases

combine. During the reaction of these gases, hydrogen atoms lose an electron.

Therefore, they have been oxidized. The oxygen atoms, on the other hand, gain two

electrons – one from each of two hydrogen atoms. The oxygen atoms have

undergone reduction. Thus, the formation of water involves both oxidation and

reduction.

The rusting of iron is a common example of oxidation. Another example is the

combustion of fuels such as natural gas. Oxidation also takes place within the

human body, as inhaled oxygen reacts with molecules of food lo produce energy,

water, and carbon dioxide.

Many important processes rely on reduction. Metal plating, for example, occurs

when metal ions are reduced - gain electrons - to form neutral atoms. When a piece

of copper is placed in a solution containing positive silver ions, the silver ions pick

up electrons from copper atoms, and a coating of silver forms on the copper.

I. Vocabulary in context oxidized - Oxidation - reductions - Redox process - oxidation

1. Any chemical reaction in which a substance loses electrons is called

………………………….

2. Any chemical reaction in which a substance gains electrons is called

………………….





3. is a term used to refer to the process in which substances lose and gain

electrons.

4. When a substance loses electrons, it is said to be ……………...

5. …………………….also occurs within the human body.


1. What is the main idea of the passage? …………………………………..

…………………………………………………………………………..

……………………………………………………………………………

2.

Do all chemical reactions occur naturally? Give examples to illustrate.…………………………………………………………………………….

……………………………………………………………………………

3. How did scientists originally define ‘oxidation’? ………………………

…………………………………………………………………………..

4. Give one example of the redox process. ………………………………..

………………………………………………………………………….

………………………………………………………………………….

5. What does ‘reduction’ mean? ………………………………………….………………………………………………………………………….

III. Grammar review

A. Combine the sentences using relative clauses

1. Scientists have discovered something. They discovered that the rare gases

are found as gases at ordinary temperatures and pressures.

……………………………………………………………………………

……………………………………………………………………………

……………………………………………………………………………

2. Helium is best known as gas in balloons and airships. Helium is used to

prevent chemical from reacting with other elements during storage and

transportation.

……………………………………………………………………………

……………………………………………………………………………







----------------------------------------------------------------------------------------------------------------------------------------------

………………………………………………………………………………………………………………………………

……………………………………………………………………………………………………………………………..

28. When activated by sunlight, nitrogen oxides and hydrocarbons undergo a

photochemical reaction. It is this reaction that produces gases called

oxidants.

-------------------------------------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------------------------------

……………………………………………………………………………………

B. Put the words in brackets into correct forms

1. Instead of (try) …………….…….. to enter a university, he applied for

a job.

2. The fact that it is hard to find the answers to the question of ‘how did

life begin” (be) ……………..many scientists do not agree with each

other entirely.

3. Reproduction (help) ………….…………….living things be able to

avoid extinction.

4. Scientists (try) …………………….…to find a general definition for

the question of 'what life is.’

5. It (seem) …………………that biology and chemistry are related to a

certain extent.

C. Vocabulary review: Choose the words to fill in the blanks

miscible – isotope – chemical behavior – chemical identity – chemical

formulas – chemical bonds – chemical equations – compounds –

solubility – solution – surface tension –Van der Walls forces – ionic

bonds – covalent bonds- catalysis

1. Electron in the outer shells control the ---------------------of an atom

2. -------------------- is a word used to refer to atoms that have the same number of

protons but different numbers of neutrons.

3. Molecules are the smallest particles in which a substance can be divided and

still have the …………………… of the original substance.

4. In a liquid, molecules move about easily, but they still have some force that

attracts them to one another called ----------------------





5. The transfer of electrons from one atom to one or more other atoms is called

--------------------------

6. We use ---------------------- to demonstrate what occurs in chemical reactions.

7. The process in which a substance increase the speed of a reaction is called -----

----------------

8. A substance’s ability to dissolve in another is called its ----------------------

9. Unlike ------------------------ , mixtures vary on composition from sample to sample.

10. Two liquids that have the ability to form a solution are described as -----------------





UNIT THIRTEEN COMPOUNDSChemical compounds may be divided into one of two groups, organic

compounds and inorganic compounds. These two groups can be split up into a few

smaller groups of compounds, each denned by its atomic structure. Acids and bases

are two important groups of compounds. Isomer is a term used to describe different

compounds that have the same molecular formula.

Organic compounds

All basic substances that make up living organisms are called organic

compounds. Carbon atoms make up the foundation of organic compounds. Most

other substances that contain carbon, particularly synthetic substances such as

plastics, are also considered organic compounds. The study of compounds that

contain carbon is called organic chemistry.

Carbon forms more compounds than any other element except hydrogen. The

basic reason for this is that carbon atoms have the ability to form an incredible

variety of chemical bonds with other carbon atoms and atoms of other elements.

Scientists have identified several million organic compounds.

Many important organic chemicals used in industry are obtained from plant and

animal sources. For example, coal, oil, and natural gas are produced from the

remains of organisms that lived millions of years ago. Other organic compounds

present in living matter include ammo acids, sugars, and nucleic acids.

Originally, scientists believed that carbon-containing compounds could only be

found from living sources. In the early 1800's, however, scientists learned that

organic compounds could be created artificially. Nearly all the plastics and synthetic

fibers we use every day are organic substances, as are such materials as artificial

sweeteners, pesticides, and many useful drugs.

In addition to their ability to form many types of bonds, carbon atoms can also

link together into very long chains. These long chains form gigantic molecules

called polymers. Polymers make up many important organic compounds. Some

polymers, such as starch and wool, occur naturally. Starch is formed by plants from

a simple sugar called glucose, and wool is a variety of protein. Other polymers aresynthetic. Nylon and polyethylene, a tough plastic material, are examples of

synthetic polymers. Rubber, another polymer, occurs naturally. But more than half

The rubber used today is made synthetically.

Inorganic compounds

Compounds that do not contain living matter are called inorganic compounds.

With a few exceptions, such as the gas carbon dioxide, inorganic compounds do not

have carbon atoms. Most inorganic compounds occur in rocks and minerals.







2. …………………..ate the base of organic compounds.

3. Plants and animals provide us with a variety of …………………..to be used

in industry.

4. Carbon-containing compounds can be found naturally and ………………..

5. Compounds that do not contain living matter are called ……………….

6. Most of inorganic compounds do not have …………………….

7. Most of inorganic compounds are made up of …………………………..

8. One of the ……………….that acids have is that they turn litmus6 paper red.

9. Two main types of acids are ……………………and ……………………..

10. Acids are one of the most common and important ………………………..


1. What is organic chemistry? ………………………………………………

……………………………………………………………………………..

2. What is the reason for the fact that carbons can form more compounds than

many other elements can? ……………………………………………

……………………………………………………………………………..

……………………………………………………………………………..

3. Where can we obtain organic compounds? ………………………………..

………………………………………………………………………………

4. Can we make organic compounds? Give examples. ………………………

……………………………………………………………………………..

5. What is polymer? ……………………………………………………………………………………………………………………………………….

6. Where can we obtain inorganic compounds? …………………………….

……………………………………………………………………………

7. What are some properties of acids? ……………………………………..

…………………………………………………………………………….

6 Quyø, giaáy quyø





8. What is one definition of acids? ………………………………………….

……………………………………………………………………………

9. What can we do with organic acids? ………………………………………

……………………………………………………………………………...

10. What are the main ideas of the text? ……………………………………….

………………………………………………………………………………

. …………………………………………………………………………….

III. Review on Vocabulary:

Fill in the blanks with given words. Use each word once only. Be careful

since there are more words than blanks. solution – strong nuclear force – Van der Waals forces – symbols – formulas –

compound – reactants – polar molecules – behavior – molecules – lose – gain –

valance – ion – isotope – covalent bonds – ionic bonds – chemical reaction –

chemical identity – suspension – chemical bonds

11. A force called --------------------------------------------- keeps the protons and neutrons

contained within the nucleus.

12. In ------------------------------------, more positive charge collects at another place.

13. -------------------------------------- is the capacity of an atom to combine with anotheratom, forming a molecule.

14. The ------------------------------------ of substances is determined by the behavior of the

atom that make up those substances.

15. The forces that hold the atoms of a molecule together are called ------------------

16. Scientists show the composition of molecules by using the ---------------------- for

elements in chemical formulas

17. The ----------------------------- in a solid vibrate but do not move about to different

part of the solid.

18. An ------------------------------- is an atom or a group of atoms with a positive or

negative electric charge

19. A ------------------------------- is formed when atoms of one element bond with atoms

of another element.

20. Atoms that tend to ------------------------------------ electrons have a positive valence.





21. ----------------------------------------- are formed when two or more atoms share pairs of

electrons.

22. A process in which one substance is chemically converted into a different

substance is called a -------------------------------------------------------- .

23. The number of atoms in the -----------------------------is the same as the number of

atoms in the products.

24. A ----------------------------------- is a mixture of two or more individual substances

that cannot be separated by a mechanical mean.

25. A -------------------------------------- is a mixture whose substances can be separated by

filtration. IV. Review on Grammar:

A. COMBINE THE SENTENCES

1. Substances make up universe. Chemistry is the scientific study of

these substances

----------------------------------------------------------------------------------------------------------------------------------------

2. There are currently 103 officially named and recognized elements.

Some of these elements do not occur naturally and must be created in

a laboratory.

---------------------------------------------------------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------------------------------------------------------

3. Atoms of a molecule are held together by some forces. We call those

forces chemical bonds.

----------------------------------------------------------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------------------------------------------------------

4. Molecules are measured by their molecular mass. The molecular massequals all the atomic masses of atoms in a molecule.

---------------------------------------------------------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------------------------------------------------------

5. A chemical reaction is a process. In this process, one substance is

chemically converted into a different substance

------------------------------------------------------------------------------------------------------------------------------------

----





------------------------------------------------------------------------------------------------------------------------------------

----

B. Turn the following sentences into passive voice

1. Many different covalent binds hold individual molecules together.

----------------------------------------------------------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------------------------------------------------------

2. We use chemical formulas to describe compounds, showing the ratio

between the elements that make up the compounds

----------------------------------------------------------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------------------------------------------------------

3. The number of electrons in the outer shell of an element’s atom determines

its chemical behavior.----------------------------------------------------------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------------------------------------------------------

4. When atoms combine, they usually form molecules.

---------------------------------------------------------------------------------------------------------------------------------------

5. Early people thought that life was created by Gods.

---------------------------------------------------------------------------------------------------------------------------------------





UNIT FOURTEEN: MIXTURES

Many substances consist of combinations of compounds. These substances are

called mixtures. Unlike compounds, mixtures vary in composition from sample to

sample. For example, spaghetti sauce is a mixture. Some samples of it may be

composed of more tomato, some may have more spices, and others may have more

water. However, they are all spaghetti sauce.

There are two basic types of chemical mixtures, solutions and suspensions. A

solution is a mixture of two or more individual substances that cannot be separated

by a mechanical means, such as filtration. A suspension is a mixture whose

substances can be separated by filtration. Also, it is possible to recognize a

suspension as a combination of two different substances. The different substances in

tomato sauce, for example, can be recognized as separate from each other. Asolution generally appears as one substance.

Solutions

Solutions occur in three forms. There are liquid solutions, solid solutions, and

gaseous solutions.

LIQUID SOLUTIONS are formed when a solid, gas, or liquid is dissolved in a

liquid. Examples include water mixed with alcohol, and sugar dissolved in tea. Two

liquids that have the ability to form a solution are described as miscible. This ability

depends on the chemical properties of the liquids and on physical conditions such as

tempera lure and atmospheric pressure. Some liquid mixtures are more misciblethan others. Water and alcohol are completely miscible because any amount of the

two substances produces a solution. Oil and water, on the other hand, are not

miscible because one will not dissolve in the other.

Gases and solids that dissolve in liquid are described as soluble. The substance

that is dissolved is called the solute, and the substance that dissolves it is the solvent .

Water is the most common solvent. Other common solvents include acetone and

alcohol. In most cases, a solvent and the substance it dissolves have similar

molecular structure. For instance, oil dissolves in gasoline.

A given volume of solvent at a particular temperature can dissolve only a certainamount of solute. For example, a particular amount of water can dissolve only a

certain amount of salt. Any additional salt remains undissolved in the water. A

substance's ability to dissolve in another is called its solubility. The solubility of

most solids depends on the chemical properties of the substances and on the

temperature of the liquid solution. For gases, solubility also depends on pressure.

Solvents have many industrial and scientific applications. They are used in the

production of cleaning fluids and such coatings as inks and paints. Solvents are also





important in the manufacture of nylon, polyethylene, and many other synthetic

fibers.

SOLID SOLUTIONS usually occur as solid forms of liquid solutions. A mixtureof melted copper and zinc, for example, is a liquid solution that cools to form brass,

a solid solution. When melted silver and copper are mixed and cooled, another solid

solution—sterling silver—is produced.

GASEOUS SOLUTIONS result from the mixture of gases. Air, for instance, is a

mixture of nitrogen and oxygen, plus smaller amounts of argon and carbon dioxide.

Gaseous solutions are completely miscible - any amount of one gas in a solution can

dissolve in any amount of the other. Physical conditions do not affect the ability of

gases to form a solution.

SuspensionsThe chemical definition of a suspension is a mixture in which the particles of a

substance separate from a liquid or gas slowly. These particles consist of many

atoms or molecules, so that they can generally be visually recognized. The particles

can be thought of as "Heating" in the mixture.

There are several types of suspensions. They include: (1) a solid in a gas, such as

dust and smoke; (2) a liquid in a gas, such as fog and aerosols; (3) a solid in a liquid,

such as muddy or soapy water; (4) a gas in a liquid, such as foam; and (5) a liquid in

a liquid, such as latex or water-based paints.

Colloids are suspensions that contain extremely small particles. The particles inmost colloids can only be seen through an electron microscope. An example of a

common colloid is homogenized milk, which has tiny particles of suspended fat.

Colloids also include such familiar products as paint and ink. Blood and many other

fluids in living things are also colloids.

I. Vocabulary soluble - solutions - Solute - Mixtures - Miscible -

suspension Solvent - Solubility

1.

…………………..are combinations of compounds.2. Two fundamental types of chemical mixtures are …………….and

……………...

3. ……………..is a word used to describe the state when two liquids have

the ability to form a solution.

4. Gases and solids that dissolve in liquid are describes as ……………...

5. ………………..is a word used to refer to the substance that is dissolved.





6. ……………….is a word used to refer to the substance that dissolves the

solute.

7. is a word used to refer to a substance’s / solid’s ability to dissolve inanother substance.

II. Comprehension questions1. What does the phrase “mixtures vary in composition from sample to

sample’’ mean? ………………………………………………………..

…………………………………………………………………………

2. What is a solution? …………………………………………………….

………………………………………………………………………….

What is a suspension? ……………………………………………………………………………………………………………………………

3. What is the difference between a solution and a suspension? ……………

……………………………………………………………………………..

4. What determines the miscibility of a substance? ………………………….

……………………………………………………………………………..

5. What determines the solubility of a solid? ………………………………..

……………………………………………………………………………..

6. What forms do solid solutions often occur? ………………………………

……………………………………………………………………………..

7. How are gaseous solution formed? ………………………………………..

………………………………………………………………………………

8. is the solubility of a gas high or low? ………………………...……………

……………………………………………………………………………..

9. What determines the ‘solubility’ of a gas? …………………………………

……………………………………………………………………………

10. How many types of suspensions are there? Give examples? ………..

…………………………………………………………………………….

III. Grammar review

A. Reorder the words to make meaningful sentences

1. shape / Forces / within / determine / its / a molecule.

----------------------------------------------------------------------------------------------------------------------------------------------

2. two or more atoms / covalent bonds / formed / share pairs of electrons / when

/ are.





-----------------------------------------------------------------------------------------------------------------------------------------------

---------------------------------------------------------------------------------------------------------------------------------------------

3. that / the force / hold / together / ionic compounds / is called / an ionic bond.-----------------------------------------------------------------------------------------------------------------------------------------------

---------------------------------------------------------------------------------------------------------------------------------------------

4. suspensions / contain / colloids / are / that / extremely small / particles.

-----------------------------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------------------------

5. compounds / Living things / the animal kingdom / are / of / or plant kingdom.

-----------------------------------------------------------------------------------------------------------------------------------------------

---------------------------------------------------------------------------------------------------------------------------------------------

6. used / manufacturing / aluminum chlorine / in / detergents / is

-----------------------------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------------------------

7. in our lives / constantly / chemical reactions / carried out / are

-----------------------------------------------------------------------------------------------------------------------------------------------

---------------------- -------------------------------------------------------------------------------------------------------------------- ----------

8. on the size / its atoms / and number of / a molecule’s size / depends

-----------------------------------------------------------------------------------------------------------------------------------------------

------------------ -------------------------------------------------------------------------------------------------------------------- --------------

9. held together / molecules / in certain arrangements / atoms / are made up of

------------------ ------------------------------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------------------------------------

10. depends partly on / the kind / the types / of volcano eruption / of ejected

material

-------------------------------------------------------------------------------------------------------------------------------------------------------

---------------------------------------------------------------------------------------------------------------------------------------------

B. Turn the following sentences into passive voice

2. Scientists obtain many important organic chemicals used in industry from

plant and animal sources.

----------------------------------------------------------------------------------------------------------------------------------------------------

-------------------------------------------------------------------------------------------------------------------------------------------------------

2. People have increasingly built houses on places where marshes once were.

-------------------------------------------------------------------------------------------------------------------------------------------------------

-------------------------------------------------------------------------------------------------------------------------------------------------------







Concrete And Salt Water

Two classic examples of mixtures are concrete and salt water. You can see them

both being made everyday. Concrete is a mixture of lime (CaO)/cement, water,

sand, and other ground-up rocks and solids. All of these are mixed together.

Workers then pour the concrete into a mold and the concrete turns into a solid

(because of the cement solidifying) with the separate pieces inside. While the

cement hardening might be a chemical reaction... The rocks and gravel are held in

place by physical forces and used for added strength. The rocks and gravel are not

chemically bonded to the cement. The gravel is also not evenly distributed, there are

still pieces here and there. The concentrations change from area to area. Salt water is

a little different. First, it's a liquid. Second, it's an ionic solution. the salt is broken

up into sodium (Na) and chloride (Cl) ions in the water.

Now you might be wondering why concrete and salt water are not new

compounds when they are all mixed together. The special thing is that the basic

parts can still be removed by physical forces. You can take the solid concrete and

grind it up again. The individual components can then be separated and you can start

all over. Salt water is even easier. All you have to do is boil the water off and the

salt is left over, just like when you started.

The thing to remember about mixtures is that you start with some pieces,

combine them, and then you can do something to pull those pieces apart again. You

wind up with the same molecules (in the same amounts) that you started with.

SOLUTIONS

Before we dive into solutions let's separate solutions from mixtures. Solutions are

groups of molecules that are mixed up in a completely even distribution. Hmmm. Not the easiest way to say it. Scientists say that solutions are HOMOGENEOUS

systems. A mixture can have a little higher concentration on one side of the liquid

than the other. Solutions have an even concentration throughout the system.

An example: Sugar in water vs. Sand in water. Sugar dissolves and is spread

throughout the glass of water. The sand sinks to the bottom. The sugar-water could

be considered a solution. The sand-water is a mixture.

Can anything be in a solution?











GLOSSARY

atoms (Unit 1) nguyeân töû

additional energy (2) naêng löôïng buø ñaép

anion (10) anion

artificially (13) nhaân taïo

atomic mass (4) khoái löôïng nguyeân töû

atomic mass unit (4) ñôn vò khoái löôïng nguyeân töû

attract (7) huùt

balance (6) caân baèng

behavior (4) phaûn öùng, tính chaát

carbon atoms (13) nguyeân töû carbon

carbon compounds (1) hôïp chaát carbon

cation (10) cation

chemical behavior (3) tính chaát hoùa hoïc

chemical bonds (6) lieân keát hoùa hoïc





chemical equation (11) phöông trình hoùa hoïc

chemical formulas (9) coâng thöùc hoùa hoïc

chemical identity (6) ñaëc ñieåm hoùa hoïc

chemical reaction (11) phaûn öùng hoùa hoïc

compound (9) hôïp chaát

covalent bonds (10) lieân keát hoùa trò

crystalline solids (8) chaát raén daïng tinh theå

definite shape (8) daïng coá ñònh

definite volume (8) khoái löôïng / dung tích coá ñònh

diatomic molecule (7) nhò phaân töû

electrical attractions (8) löïc huùt / haápp daãn ñieän töø

electrically neutral (4) trung hoøa veà ñieän

electricity (2) ñieän

electron (2) electron

element (5) nguyeân toá





empty space (3) khoâng gian troáng

energetic (8) maïnh, doái daøo naêng löôïng

energy (3) naêng löôïng

energy changes (1) thay ñoåi veà naêng löôïng

equal (9) caân baèng

experimental foundation (1) neàn taûng veà maët thöïc tieãn, lyù thuyeát

forces (7) löïc

forces of attraction (8) löïc haápp daãn

formulas (5) coâng thöùc

independent linear motion (8) chuyeån ñoäng tuyeán tính ñoäc laäp (theoñöôøng thaúng)

inorganic (13) voâ cô

inorganic acids (13) acid voâ cô

ionic bond (10) lieân keát i-on

ionic compound (10) hôïp chaát i-on





isotope (3) ñoàng vò

mass (3) khoái löôïng, troïng löôïng

mass number (4) soá khoái

miscible (14) coù theå troän laãn,coù theå taïo hoãn hôïp vôùi

molecular mass (6) khoái löôïng phaân töû

molecule (7) phaân töû

motion (8) chuyeån ñoäng

negative (2) aâm (ñieän tích)

negative ion (4) i-on aâm

negative valance (9) hoaù trò aâm

neutron (2) nô tron

non-mental elements (13) nguyeân toá phi kim loaïi

nucleus (6) haït nhaân

opposite charges attraction (2) löïc huùt do traùi daáu ñieän tích





organic acids (13) a-xit höõu cô

organic compounds (13) hôïp chaát höõu cô

oxidation (12) oâ – xi hoùa

particles (8) phaàn töû

physical change (11) thay ñoåi veà maët vaät lyù

polar molecules (6) phaân töû coù caùc electrons coù xu höôùng doàn

veà hai cöïc / hai ñaàu cuûa nguyeân töû

positive (2) döông (ñieän)

positive ion (4) i-on döông

positive valance (9) hoaù trò döông

product (11) chaát taïo ra sau phaûn öùng

property (13) tính chaát

protons (2) pro-ton

pure forms (5) hình thöùc nguyeân chaát, khoâng pha taïp

ratio (9) tæ leä





reactant (11) chaát tham gia phaûn öùng

redox process (12) quaù trình oâ-xi hoùa khöû

reductions (12) quaù trình khöû

revolve (10) quay voøng

shapes (7) hình daïng

shells (3) lôùp (ñieän töû)

solid (8) chaát raén

solubility (14) tính tan

soluble (14) coù theå hoøa tan

solute (14) chaát tan

solutions (14) dung dòch

solvent (14) dung moâi

spin around (3) quay troøn

stable (9) oån ñònh, vöõng beàn










REFERENCES:Luder, Vernon, & Zuffanti. (1953). General Chemistry. W. B. Saunders

Company – Philadelphia and London.

World Book, Inc. (1994). The World Book of SCIENCE POWER – Version

No 1 – Chemistry, Physics, and Life Sciences. United States. ISBN 0-

7166-2294-7

Web sites: http://www.chemtutor.com/

http://www.tannerm.com/

http://www.chem4kids.com/

Documents

Tiếng Anh B4 (Dành cho sinh viên khoa hoá học) Tác giả: Nguyễn Tất Thắng Trường Đại học Đà Lạt, 2009