DAILY ASSIGNMENT

• HOW ARE ITEMS IN A GROCERY STORE ORGANIZED?

• WHAT IF ITEMS WERE ORGANIZED ALPHABETICALLY?

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The Periodic Table

Chapter 5MENDELEEV'S TABLE

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Why is the Periodic Table important to me?

• The periodic table is the most useful tool to a chemist.

• You get to use it on every test.

• It organizes lots of information about all the known elements.

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Pre-Periodic Table Chemistry …

• …was a mess!!!• No organization of

elements.• Imagine going to a grocery

store with no organization!!• Difficult to find information.• Chemistry didn’t make

sense.

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Dmitri Mendeleev: Father of the Table

HOW HIS WORKED…• Put elements in rows by increasing atomic weight.• Put elements with similar properties in columns.• In column, element masses increase from top to

bottom.• Periodic table: arrangement of elements in

columns, based on a set of properties that repeat from row to row.

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Dmitri Mendeleev: Father of the Table

SOME PROBLEMS…• Blank spaces for what he said were

undiscovered elements. • Predict properties of undiscovered elements by

looking at nearest elements.• New elements were discovered based on

Mendeleev’s predictions (Turned out he was right!).

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THE MODERN PERIODIC TABLE

• Mendeleev wasn’t too far off.• Now the elements are put in rows by increasing

ATOMIC NUMBER!!• The horizontal rows are called periods and are

labeled from 1 to 7. (# elements/period varies based on energy---electron levels)

• The vertical columns are called groups are labeled from 1 to 18.

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Groups…Here’s Where the Periodic Table Gets Useful!!

• Elements in the same group have similar chemical and physical properties based on atomic number

Why??

• Elements in group have similar electron configurations.

• Periodic Law: members of a group have repeating properties.

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4 PIECES OF INFO.

• NAME• SYMBOL• ATOMIC NUMBER• ATOMIC MASS –

given in atomic mass units (1/12 mass of C-12.

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4.0026

CLASSES OF ELEMENTS

ELEMENTS CLASSIFIED AS:1. STATES: SOLID (Black), LIQUID (Purple), OR

GAS (Red)2. OCCURRENCE: NATURALLY AND NOT

NATURALLY (White)3. PROPERTIES:METALS METALOIDS NONMETALS

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METALS• METALS: good conductors heat and

electricity– Solid at room temp. (except Hg)– Most are malleable (hammered w/o

shattering)– Most are ductile (made in thin wire)

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METALS ---- CONTINUED

• TRANSITION METALS: Groups 3-12– Bridge between elements on left and

right of table– Ability to form compounds with distinctive

colors– EXAMPLE: Many used to make colored glass

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NONMETALS

• NONMETALS: Poor conductors heat and electricity– Many are gases at room temp.– All gases are nonmetals

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METALLOIDS

• METALLOIDS: Elements with properties between metals and nonmetals– Ability to conduct electricity varies with temp.

PERIODMETALLIC NONMETALLIC

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Period Table

• As you move from left to right on the table, the elements become less metallic and more non-metallic.

• As you move up and down, the rows are determined by the maximum number of energy levels.

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Daily Assignment

• What elements are found in your body?• Hint: think about your Flintstones vitamins!

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Daily Assignment

• Oxygen, Nitrogen, Sulfur, Hydrogen, Iodine, Carbon, Iron, Potassium, Zinc

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Valence Electrons• Why do certain chemicals combine violently?• What causes elements to bond together?• The answer is Valence Electrons.

– The electrons contained in the outermost energy level that determine an element’s chemical and physical properties.

Valence Electrons

• The number of valence electrons determines how reactive an element is, and this is how the groups are arranged.

• 8 is the magic number• The closer an element gets to 8, or “full,” the

HAPPIER it will be.• We want to make happy elements, right?

Valence Electrons

• Elements will gain, lose, or share electrons to make a full valence shell. If an element has one in the valence, it doesn’t really like it there, and will give up that electron to drop down to a full energy level.

Unlikely Partners

• Element number 11, Sodium, reacts violently with water. When it combines with number 17, Chlorine (which is a poisonous gas) it forms something you use every day. Why do these two dangerous substances react so well together?

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Groups and Periods

• The periodic table is arranged in several ways, but the easiest to see are rows and columns.

• The columns, or groups, are determined by the elements’ physical and chemical properties, which are similar within the group.

• The row, or period, is determined by the maximum number of electrons in the valence.

Families on the Periodic Table

• Columns are also grouped into families.

• Families may be one column, or several columns put together.

• Families have names rather than numbers. (Just like your family has a common last name.)

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Hydrogen

• Hydrogen belongs to a family of its own.

• Hydrogen is a diatomic, reactive gas.

• Hydrogen was involved in the explosion of the Hindenberg.

• Hydrogen is promising as an alternative fuel source for automobiles

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Alkali Metals

• 1st column on the periodic table (Group 1) not including hydrogen.

• Very reactive metals, always combined with something else in nature (like in salt).

• Soft enough to cut with a butter knife

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Alkaline Earth Metals

• Second column on the periodic table. (Group 2)

• Reactive metals that are always combined with nonmetals in nature.

• Several of these elements are important mineral nutrients (such as Mg and Ca

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Transition Metals

• Elements in groups 3-12• Less reactive harder

metals• Includes metals used in

jewelry and construction.• Metals used “as metal.”

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Boron Family

• Elements in group 13• Aluminum metal was

once rare and expensive, not a “disposable metal.”

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Carbon Family• Elements in group 14• Contains elements

important to life and computers.

• Carbon is the basis for an entire branch of chemistry.

• Silicon and Germanium are important semiconductors.

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Nitrogen Family• Elements in group 15• Nitrogen makes up over

¾ of the atmosphere.• Nitrogen and phosphorus

are both important in living things.

• Most of the world’s nitrogen is not available to living things.

• The red stuff on the tip of matches is phosphorus.

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Oxygen Family or Chalcogens

• Elements in group 16• Oxygen is necessary for

respiration.• Many things that stink,

contain sulfur (rotten eggs, garlic, skunks,etc.)

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Halogens

• Elements in group 17• Very reactive, volatile,

diatomic, nonmetals• Always found combined

with other element in nature .

• Used as disinfectants and to strengthen teeth.

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The Noble Gases

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The Noble Gases

• Elements in group 18• VERY unreactive,

monatomic gases• Used in lighted “neon”

signs• Used in blimps to fix the

Hindenberg problem.• Have a full valence shell.

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Lanthanides and Actinides

• You may be saying, Mr. Genovese, why are there two rows on the bottom?

• If you look closely, they actually fit up into the periodic table.

• They were put there to make it more concise and because they have characteristics that make them similar.