8/3/2019 Intro to Chemistry_Pre-AP
1/75
Unit 1: Introduction to
ChemistryPre- AP Chemistry
Edmond NorthHigh School
Chapters: 1 & 2
8/3/2019 Intro to Chemistry_Pre-AP
2/75
Scientific Method / Process
The Scientific Method is asystematic approach to problemsolving.
It is generally composed of thefollowing parts:
Question
HypothesisExperimentData AnalysisConclusion
8/3/2019 Intro to Chemistry_Pre-AP
3/75
Measurement
Measurement: A quantitative observation consisting of anumeric value and units.Three are 2 kinds of units: base and derived
Base Units: Units are mutually independent of each otherEx: 7 meters, 30 kg, 6 seconds
Derived Units: Units are obtained mathematically from baseunits
Ex: 10 cm3, 0.9 g/mL, 22 meters/second
8/3/2019 Intro to Chemistry_Pre-AP
4/75
Metric System
The Metric System is a decimalized system of measurement based on powers of 10
Used internationally and in the scientific communityConsists of base units and prefixes
The United States,Liberia, andMyanmar (Burma)are the only threecountries who donot use the metricsystem
8/3/2019 Intro to Chemistry_Pre-AP
5/75
Metric System - Base Units
Mass
TimeTemperature
Volume
Distance
grams (g)
meters (m)
liters (L)
Kelvin (K) seconds (s)
8/3/2019 Intro to Chemistry_Pre-AP
6/75
Accuracy & Precision
Accuracy: the degree of agreement between thetrue value and the
measured value(bullseye)Precision: the degree of agreement amongseveral measured values(grouping)
8/3/2019 Intro to Chemistry_Pre-AP
7/75
Accuracy & Precision
Three different groups of students measure the mass of amedal, with a known value of 5.000 grams. Evaluateeach groups data for its accuracy and precision (low or
high):
Trial 1 5.003 g
Trial 2 5.002 g
Trial 3 5.001 g
Trial 1 5.400 g
Trial 2 5.202 g
Trial 3 5.905 g
Trial 1 5.503 g
Trial 2 5.499 g
Trial 3 5.501 g
Group 2 Group 1 Group 3
Accuracy ______ Precision ______
Accuracy ______ Precision ______
Accuracy ______ Precision ______
high high
low low high
low
8/3/2019 Intro to Chemistry_Pre-AP
8/75
Uncertainty in Measurement
All measuring instrumentshave a degree of uncertainty .The more divisions a devicehas, the more accurate themeasurement.The last digit of a measurementis always estimated (uncertain).
How would you read thevolume in this graduatedcylinder if the markingsshowed every 5 mL instead of every 1 mL?
read from thebottom of themeniscus
8/3/2019 Intro to Chemistry_Pre-AP
9/75
Uncertainty in Measurement
If we measure the length of the paw print with adecimeter ruler, we know for a certainty that it isbetween 0 and 1 decimeters. We estimate the nextdigit:
0.3 decimetersestimated digit
8/3/2019 Intro to Chemistry_Pre-AP
10/75
Uncertainty in Measurement
If we measure the length of the paw print with acentimeter ruler, we know for a certainty that it isbetween 3 and 4 centimeters. We estimate thenext digit:
3.5 centimetersestimated digit
8/3/2019 Intro to Chemistry_Pre-AP
11/75
Uncertainty in Measurement
If we measure the length of the paw print with amillimeter ruler, we know for a certainty that it isbetween 34 and 35 millimeters. We estimate thenext digit:
34.5 millimetersestimated digit
8/3/2019 Intro to Chemistry_Pre-AP
12/75
Significant Figures
Significant Figures are the digits in a measurement that are knownwith some degree of certainty are called significant figures.
The number of significant figures in a measurement = the number of digits that are known + the estimated digitThe more significant figures after the decimal, the more accurate themeasurement.
Ex: This triple beambalance shows amass of 62.41grams. There are 4
significant figures inthis measurement.
8/3/2019 Intro to Chemistry_Pre-AP
13/75
Significant Figure Rules
There are rules forcounting significantfigures related to:
Non-zero integersZeroes
Leading zeroesCaptive zeroes
Trailing zeroes
8/3/2019 Intro to Chemistry_Pre-AP
14/75
Significant Figure Rules
Non-zero integers are always significant
3456 cm has4 sig figs
8/3/2019 Intro to Chemistry_Pre-AP
15/75
Significant Figure Rules
Leading zeroes are never significant
0.0 486 g has3 sig figs
8/3/2019 Intro to Chemistry_Pre-AP
16/75
Significant Figure Rules
Captive zeroes are always significant
16. 07 mL has4 sig figs
8/3/2019 Intro to Chemistry_Pre-AP
17/75
Significant Figure Rules
Trailing zeroes are only significant if the numbercontains a decimal
9.3 0 m has
3 sig figs 93 0 m has2 sig figs
8/3/2019 Intro to Chemistry_Pre-AP
18/75
Significant Figures Practice
How many significant figures are in the followingmeasurements?1. 8,675,309 km ____2. 90,210 L ____3. 0.07 mg ____4. 0.2020 daL ____
5. 300.00 g ____
7
414
5
8/3/2019 Intro to Chemistry_Pre-AP
19/75
8/3/2019 Intro to Chemistry_Pre-AP
20/75
Scientific Notation Rules
CoefficientsCoefficients must be greater than or equal to 1 and less than 10Coefficients can be positive or negativeAll numbers in the coefficient are counted as significant
Which of the following numbers are writtenincorrectly?
22 x 10 5 9.5 x 10 2 10 x 10 8
7 x 10 -3 0.3 x 10 -9 -1.00 x 10 6
8/3/2019 Intro to Chemistry_Pre-AP
21/75
Scientific Notation RulesBases
Base is always a 10Bases are never counted as significant
ExponentsExponents are always integersExponents can be positive (big number) or negative (small number)
Ex: 1 x 103 = 1000 and 1 x 10-3 = 0.001Exponents are never counted as significant
Which of the following numbers are written incorrectly?
4.1 x 10 -5 2.2 x 6 20 1.0 x 10 -1
7 x 10 0 0.15 x 10 -9 -7 x 10 6.3
8/3/2019 Intro to Chemistry_Pre-AP
22/75
Scientific Notation
How to enter the number 2.5 x10 -8 into the calculator:
Enter the coefficient 2.5
Press 2nd, then EE
Enter the exponent -8
It should appear on yourscreen as 2.5E-8
8/3/2019 Intro to Chemistry_Pre-AP
23/75
Significant Figure OperationsMultiplication & Division
Calculate raw answer Rounded answer must contain no more significant figures than themeasurement with the least number of significant figures
Example: What is the density of a bar of gold with a mass of 87.82 g anda volume of 4.55 cm 3? (Density = mass volume)
87.82 g 4.55 cm 3 = 19.301099 g/cm 3 19.3 g/cm 3
4 sig figs 3 sig figs raw answer 3 sig figs
8/3/2019 Intro to Chemistry_Pre-AP
24/75
Significant Figure Operations
Addition & SubtractionCalculate raw answer Rounded answer can have no more digits to the right of the decimalpoint than the measurement with the least number of digits to theright of the decimal point
Example: What is the difference in length between a professional shotput throw of 23.125 meters and an amateur shot put throw of 21.2meters?
23.125 m 21.2 m = 1.925 m 1.9 m3 digits 1 digit raw 1 digit
after decimal after decimal answer after decimal
8/3/2019 Intro to Chemistry_Pre-AP
25/75
Exact Numbers
Exact Numbers are differentfrom measurements becausethey have no uncertaintySignificant figures does notapplyExamples
Conversions (3 feet = 1 yard)Counting Numbers (20 M&Ms)
8/3/2019 Intro to Chemistry_Pre-AP
26/75
Metric System - PrefixesPrefix Symbol Numeric Representation
tera- T 10 12 1,000,000,000,000
giga- G 10 9 1,000,000,000
mega- M 10 6 1,000,000
kilo- k 10 3 1,000hecto- h 10 2 100
deka- da 10 1 10
(base unit) (none) 10 0 1
deci- d 10 -1 0.1
centi- c 10 -2 0.01
milli- m 10 -3 0.001
micro- 10 -6 0.000001
nano- n 10 -9 0.000000001
pico- p 10 -12 0.000000000001
8/3/2019 Intro to Chemistry_Pre-AP
27/75
Powers of Ten
8/3/2019 Intro to Chemistry_Pre-AP
28/75
Remember
K ing H enry d ied by drinkingchocolate m ilk.
Kilo Hecto Deka Base Deci, Centi,and Milli.
8/3/2019 Intro to Chemistry_Pre-AP
29/75
Metric Conversions
Example: How many kilograms are in 75decigrams?
Example: How centiliters are in 12 dekaliters?
Move decimal 4 places to the left: 75 dg = 0.0075 kg
Move decimal 3 places to the right: 12 daL = 12,000 cL
(start)
k h da d c m base x x
k h da d c m base x x
(start)
8/3/2019 Intro to Chemistry_Pre-AP
30/75
Metric Conversions Practice
Practice metric conversions:
1. _______ dg = 4.2 hg2. _______ dam = 6,055 mm3. _______ L = 1 cL
4. _______ cK = 0.003 kK5. _______ s = 11,700,000 s
k h da d c m base x x
4,2000.6055
0.01
30011.7
8/3/2019 Intro to Chemistry_Pre-AP
31/75
Metric System: Pressure
Pressure is the force over a given areaIf someone stepped on your foot, which shoe would you preferthey wore?
Pressure is measured in units of:1 Atmospheres (atm)101.3 kiloPascals (N/m 2)760 mmHg (mm of Mercury)
760 torrsPressure is measured by 2 instruments:
BarometerManometer
8/3/2019 Intro to Chemistry_Pre-AP
32/75
Pressure Conversions
400 torr = __________ kPa400 torr 101.3kPa = 53.32kPa
760 torr
328 mmHg = __________ atm328mmHg 1atm = 0.432atm
760 mmHg
1 atm = 760 torr = 760 mmHg = 101.3 kPa
8/3/2019 Intro to Chemistry_Pre-AP
33/75
Density
Density is the ratio of anobjects mass and volume
The formula for density is D =
m / vIn chemistry, the 2 mostcommon units of density willbe g/mL and g/cm 3
The four cubes to the right havethe same volume (1 cm 3), butdifferent masses. How does this
effect their densities?
8/3/2019 Intro to Chemistry_Pre-AP
34/75
Density
The density of an object is an intensivephysical property , meaning it cannot bechanged no matter the quantity
A property that changes with the amount or quantity of thesubstance is an extensive property.
The density of water is 1 g/mLObjects that float < 1 g/mLObjects that sink > 1 g/mL
What happens to the density of an objectwhen it is sawed I half?
8/3/2019 Intro to Chemistry_Pre-AP
35/75
8/3/2019 Intro to Chemistry_Pre-AP
36/75
The Mole
In the same way a dozen is worth 12,a mole is worth 6.02 x 10 23
This number is called Avogadrosnumber
Mole is abbreviated as mol
Written in expanded form, thatnumber is:602,000,000,000,000,000,000,000
The mole is a large number becauseparticles are so small, it takes manyof them make up an amount we cansee and understand
We can use it to count anything!
8/3/2019 Intro to Chemistry_Pre-AP
37/75
The Mole
1 dozen cookies = 12 cookies1 mole of cookies = 6.02 X 10 23 cookies
1 gross cars = 144 cars1 mole of cars = 6.02 X 10 23 cars
1 ream Al particles = 500 Al particles1 mole of Al particles = 6.02 X 10 23 particles
8/3/2019 Intro to Chemistry_Pre-AP
38/75
Mole Calculations
6.02 x 10 23 particles = 1 mole
Ex: How many particles are in 3.00 moles of N 2?3.00 mol N 2 6.02 x 10 23 particles =
1 mol N 2Ex: How many moles of Na are in 1.10 x 10 23 particles?
1.10 x 10 23 particles Na 1 mol Na =6.02 x 10 23 particles Na
1.81 x 10 24 particles
1.83 x 10 22 moles
8/3/2019 Intro to Chemistry_Pre-AP
39/75
2 Unit Conversions
Convert the density of titanium (4.54g/mL) tokg/L.
Convert 13.2 mg/mL to g/cm 3.
8/3/2019 Intro to Chemistry_Pre-AP
40/75
Classifying Matter
8/3/2019 Intro to Chemistry_Pre-AP
41/75
Pure Substances
Pure substances cannot be separated by physicalmeans
Elements: cannot be chemically separated, listed on the periodic table
Compounds: can be chemically separated, made up of elements
carbon (C) sulfur (S) copper (Cu) mercury (Hg)
salt (NaCl) water (H 2O) sugar (C 6H12O6) rust (Fe 2O3)
8/3/2019 Intro to Chemistry_Pre-AP
42/75
Pure Substances
Particle representations of Elements
Compounds
8/3/2019 Intro to Chemistry_Pre-AP
43/75
Periodic Table
Each square on the periodictable contains:Name of Element
SymbolFirst letter is upper case, secondletter must be lower case
Atomic MassNumber (usually with a decimal)indicates the mass (g) of 1 mole of that element
Atomic Number
8/3/2019 Intro to Chemistry_Pre-AP
44/75
Types of Elements
8/3/2019 Intro to Chemistry_Pre-AP
45/75
8/3/2019 Intro to Chemistry_Pre-AP
46/75
Period/Series
8/3/2019 Intro to Chemistry_Pre-AP
47/75
The Mole
8/3/2019 Intro to Chemistry_Pre-AP
48/75
Molar Mass of Atoms
How do chemists count Avogadros number? By measuring mass (just like how they countaluminum cans for recycling)
The mass (think grams) of one mole of a substance
Atomic masses are based on the mass of carbonOne mole of carbon contains 6.02 x 1023 atoms of C
1 carbon atom is 12.011 amu
1 mole of carbon is 12.011 grams
8/3/2019 Intro to Chemistry_Pre-AP
49/75
Molar Mass of Atoms
The mass of 1 mole (in grams)Equal to the numerical value of the average
atomic mass (get from periodic table)Examples:
1 mole of C atoms = 12.0 g
1 mole of Mg atoms = 24.3 g1 mole of Cu atoms = 63.5 g
8/3/2019 Intro to Chemistry_Pre-AP
50/75
Practice
Find the molar mass1 mole of Au atoms =
1 mole of Sn atoms =
8/3/2019 Intro to Chemistry_Pre-AP
51/75
Chemical Formulas
The chemical formula describes a compoundusing numbers and element symbols
Subscript s denote number of each element in a compoundEx: H
2O has 2 hydrogens and 1 oxygen
Ex: Al 2(SO 4)3 has 2 aluminums, 3 sulfurs, and 12 oxygens
Coefficients act as a scalar (also called a multiplier)Ex: 6H 2O has 12 hydrogens and 6 oxygensEx: 3Al 2(SO 4)3 has 6 aluminums, 9 sulfurs, and 36 oxygens
8/3/2019 Intro to Chemistry_Pre-AP
52/75
Binary Ionic Compounds
A Binary Ionic Compound contains 2 elements:metal & nonmetalWhen you write a formula, you add subscripts tothe symbols for the ions until the algebraic sum of the ions charges is zero.Naming:
Name the metalDrop the end of nonmetal and add ide
Example: MgCl 2 = magnesium chloride
8/3/2019 Intro to Chemistry_Pre-AP
53/75
Diatomic Elements
Some elements are always found as a pair(2 together)
H2, O 2, N 2, F2, Cl 2, Br 2, I2Try to remember HOF BrINCl
Example:How many atoms of O are present in 78.1 g of oxygen?
Practice:How many grams of Cl are present in 100 atoms of chlorine?
78.1 g O 2 = Xg32.0 g O 2 2(6.02 X 10 23 atoms O)
8/3/2019 Intro to Chemistry_Pre-AP
54/75
Classifying Matter
8/3/2019 Intro to Chemistry_Pre-AP
55/75
Mixtures
Mixtures are composed of two or more substancesthat can be separated by physical means; containselements and/or compounds
Heterogeneous Mixtures : not uniform throughoutHomogeneous Mixtures: uniform throughout
Particle representations of mixtures
8/3/2019 Intro to Chemistry_Pre-AP
56/75
Heterogeneous Mixtures
HeterogeneousMixture: two or more
substancesphysically combined;not uniformthroughoutEx: Granite, chexmix
8/3/2019 Intro to Chemistry_Pre-AP
57/75
Suspensions
A suspension is aheterogeneous fluidcontaining solid particles
that are sufficiently largefor sedimentation.The internal phase (solid)is dispersed throughoutthe external phase (fluid)through mechanical
Suspensions willeventually settle.
8/3/2019 Intro to Chemistry_Pre-AP
58/75
Homogeneous Mixtures
Homogeneous Mixture:two or more substances
physically combined;uniform throughoutKnow as a solution composed of
Solute: substance being dissolved(smaller amount)
Solvent: substance that does thedissolving (larger amount)
Examples: kool-aid, brass
8/3/2019 Intro to Chemistry_Pre-AP
59/75
Separating a Mixture
Separating a mixture -components are separatedwithout changing their physical
identity
8/3/2019 Intro to Chemistry_Pre-AP
60/75
8/3/2019 Intro to Chemistry_Pre-AP
61/75
Magnetism
Separates metals (such asiron) from a mixture
8/3/2019 Intro to Chemistry_Pre-AP
62/75
Filtration
Separates solid substancesfrom liquids and solutions
8/3/2019 Intro to Chemistry_Pre-AP
63/75
Evaporation
Separates a dissolvedsolid from its solvent
8/3/2019 Intro to Chemistry_Pre-AP
64/75
Distillation
Separates homogeneousmixture with differentboiling points (heat
mixture and catchcondensed vapor)
8/3/2019 Intro to Chemistry_Pre-AP
65/75
Centrifuging
Separates heavierparticles (bottom of tube)from lighter particles (top
of tube) by spinningthem at high speeds
8/3/2019 Intro to Chemistry_Pre-AP
66/75
Chromatography
Separates substances on the basis of their differences insolubility in a solvent - different substances areattracted to paper or gel and move at different speeds
8/3/2019 Intro to Chemistry_Pre-AP
67/75
Properties of Matter
A property is a characteristic that describe matteror how it behavesPhysical determined without a chemical change
Extensive vary with amount of matter (Ex. Mass, volume, length, area)Intensive does not vary with amount (Ex. Density, color, odor, melting point, solubility)
Chemical can only be determined by a chemical
changeEx. Flammability, reactivity with acid, stability of a compound (how easily itdecomposes)
8/3/2019 Intro to Chemistry_Pre-AP
68/75
Changes of Matter
Physical Changes do not involve a change inchemical identity
Ex: boiling, freezing, melting, dissolving, evaporating, and crystallizing
http://images.google.com/imgres?imgurl=http://www.iamtonyang.com/0411/boiling_water.jpg&imgrefurl=http://www.tlhines.com/blog/2005_04.php&h=480&w=640&sz=82&hl=en&start=13&usg=__5ihCVULSr8HORAl9faRZZTNz2kk=&tbnid=gSv9fSHKHnBC7M:&tbnh=103&tbnw=137&prev=/images?q=boiling&gbv=2&hl=enhttp://en.wikipedia.org/wiki/Image:Sugar_2xmacro.jpghttp://images.google.com/imgres?imgurl=http://www.bu.edu/sjmag/news-cms/photos/420IceCubeEarth.jpg&imgrefurl=http://www.bu.edu/phpbin/news-cms/news/?dept=1127&id=47227&template=228&h=282&w=420&sz=117&hl=en&start=17&usg=__vT1cywjrGcqaA1nSOe47hL8Ty_M=&tbnid=JjR9Pq9psnVHFM:&tbnh=84&tbnw=125&prev=/images?q=ice+water&gbv=2&hl=en8/3/2019 Intro to Chemistry_Pre-AP
69/75
Changes of Matter
Chemical Changes newsubstances are formed inthe reaction
Ex: iron rusting, copperoxidizing, wood burning,silver tarnishing
http://images.google.com/imgres?imgurl=http://www.learner.org/channel/courses/essential/physicalsci/images/s4.rusty_nail.jpg&imgrefurl=http://www.learner.org/channel/courses/essential/physicalsci/session4/closer1.html&h=300&w=300&sz=34&hl=en&start=1&usg=__pHUV6xZ128_RBS1zA2664AQQ1ak=&tbnid=ZHnprrbo0b7rgM:&tbnh=116&tbnw=116&prev=/images?q=rusty+nail&gbv=2&hl=en8/3/2019 Intro to Chemistry_Pre-AP
70/75
Evidence for Changes of Matter
Color ChangeGas produced
without heatingPrecipitate formedNew odor develops
Large amount of heator light produced
http://images.google.com/imgres?imgurl=http://www.popsci.com/files/imagecache/photogallery_image/files/articles/salt_ss_fire2.jpg&imgrefurl=http://www.popsci.com/diy/gallery/2006-10/making-salt-hard-way&h=340&w=440&sz=31&hl=en&start=26&usg=__QWTVueELH4iukDKbJHITGgw848g=&tbnid=rF9IF9RY8XrAaM:&tbnh=98&tbnw=127&prev=/images?q=sodium+fire&start=18&gbv=2&ndsp=18&hl=en&sa=Nhttp://images.google.com/imgres?imgurl=http://www.powerlabs.org/images/ln2dem3.jpg&imgrefurl=http://www.powerlabs.org/ln2demo.htm&h=292&w=300&sz=13&hl=en&start=16&usg=__0FY2KGjpxBujASqe9iB4WddgJww=&tbnid=ErTXpg9dFXLePM:&tbnh=113&tbnw=116&prev=/images?q=gas+balloon+flask&gbv=2&hl=en8/3/2019 Intro to Chemistry_Pre-AP
71/75
Law of Conservation of Mass
The LCM says matter is neither created nordestroyed during a chemical change
The mass of the reactants is always the same as the mass of the products.The number of atoms of each element is always the same in the reactants and the products.
8/3/2019 Intro to Chemistry_Pre-AP
72/75
LCM Examples
Calcium chloride and sodium sulfate combine to formcalcium sulfate and sodium chloride.
CaCl 2 + Na 2SO 4 CaSO 4 + 2NaCl
Before and After:Does the mass change?
8/3/2019 Intro to Chemistry_Pre-AP
73/75
8/3/2019 Intro to Chemistry_Pre-AP
74/75
Heat (Thermal) Energy
Heat is a form of energy that flows between twosamples of matter because of their difference intemperature
Heat flows from hot to coldIt can be absorbed or releasedMeasured in units of calories orJoules
8/3/2019 Intro to Chemistry_Pre-AP
75/75
The End
Be Prepared for Unit 1 Test.
Recommended