1. What is Chemistry
The science that deals with matter, and the changes that matter undergoes.

2. Physical Change
Physical state is altered, but composition is the same.
SOLID  LIQUID Melting
LIQUID  GAS Boiling
GAS  LIQUID Condensing
SOLID GAS Sublimation
GAS  SOLID Reverse sublimation or deposition
LIQUID  SOLID Freezing

3. Wolpa/Advanced Placement Chemistry
Physical Change: the composition of the substance remains the same but the state changes.
Wolpa/Advanced Placement Chemistry

4. Physical Properties Color Odor Density Hardness Solubility
Melting Point
Boiling Point

5. Chemical Change
Exhibited when a substance reacts with other substances
Atoms are rearranged to form a new substance
Often observable such as color change or change in energy

6. Chemical Change: a new substance is formed.
Wolpa/Advanced Placement Chemistry

7. Extensive and Intensive Properties
An extensive property of a material depends upon how much matter is is being considered.
mass
length
volume
An intensive property of a material does not depend upon how much matter is is being considered.
density
malleability
color
Wolpa/Advanced Placement Chemistry
1.6

8. Elements and the Periodic Table
Each element is represented by a name and a symbol. (Periods/groups - alkali metals, alkaline earth metals, halogens, noble gases)
The first letter is always capitalized the second (and third) are never capitalized.
Wolpa/Advanced Placement Chemistry

9. Wolpa/Advanced Placement Chemistry
Compound
A unique substance composed of two or more elements that are chemically combined (i.e. joined intimately, not just mixed together)
Pure compounds have definite compositions and properties
Require complex chemical procedures to separate into simpler substances (elements)
Compounds include water, table salt, sugar, etc
Wolpa/Advanced Placement Chemistry

10. Wolpa/Advanced Placement Chemistry
Density
ratio of the mass of a substance to the volume of that mass
usually measure in g/mL for solids and liquids; g/L for gases
also a conversion factor relating the mass of a substance to it’s volume
Specific gravity is the ratio of the mass of a substance to the mass of an equal volume of water
Wolpa/Advanced Placement Chemistry

11. Wolpa/Advanced Placement Chemistry
A mixture is a combination of two or more substances in which the substances retain their distinct identities.
Homogenous mixture – composition of the mixture is the same throughout.
Heterogeneous mixture – composition is not uniform throughout. ?
Wolpa/Advanced Placement Chemistry

12. Wolpa/Advanced Placement Chemistry
Mixtures
Combinations of two or more substances
Can be separated by exploiting different physical properties (filtration, distillation, crystallization, chromatography)
Have chemical and physical properties that are different from the substances that make them up
The percentages by mass of the components of a mixture can be varied continuously
Wolpa/Advanced Placement Chemistry

13. No Calculator Vomit!!
We want to use the correct number of Significant Figures!
On the AP exam, you have to be within 1 sig fig in order to receive credit!

14. Counting Significant Figures
Atlantic / Pacific Method
a. Absent Decimal- Start on “atlantic” side of number & cross out all zeroes until 1st nonzero digit is reached, remaining digits are significant
b. Present decimal- start on the “pacific” side of the number & cross out all zeros until the 1st nonzero digit Is reached, remaining digits are significant

15. SI Units Measurement Unit Symbol Mass Kilogram kg Length Meter M Time
Second s
Temperature
Kelvin K
Quantity
Mole
mol
Energy
Joule J
Pressure
Pascal Pa

16. Converting between units
The standard method to convert between two different units is the factor-label or dimensional analysis method
Dimensional analysis converts a measurement in one unit to another by the use of a conversion factor
Conversion factors are developed from relationships between units
Wolpa/Advanced Placement Chemistry

17. Wolpa/Advanced Placement Chemistry
The speed of sound in air is about 343 m/s. What is this speed in miles per hour?
meters to miles
seconds to hours
1 mi = 1609 m
1 min = 60 s
1 hour = 60 min
343 m s x
1 mi
1609 m
60 s
1 min x
60 min
1 hour x
= 767 mi
hour
Wolpa/Advanced Placement Chemistry

18. Temperature and its Measurement
Temperature - measure of the intensity of the heat of a substance
Thermometer - device to measure temperature
Kelvin - K - SI unit of temperature
Celsius - °C - commonly used unit
Fahrenheit - °F - only used in USA
Wolpa/Advanced Placement Chemistry

19. Temperature conversion factors
Celsius to Kelvin
K = T in oC + 273
Kelvin to Celsius
oC = T in K - 273
Celsius to Fahrenheit
oF = (1.8 (T in oC)) + 32
Fahrenheit to Celsius
(T in oF - 32)/1.8

20. Measurements and Units
Measurement - determines the quantity, dimensions or extent of something
1.Consist of two parts
a. a numerical quantity (1.23)
b. a specific unit (meters)
Unit - a definite quantity adapted to as a standard of measurement

21. Features of Measured Quantities
When we measure a number, there are physical constraints to the measurement
Instruments and scientists are not perfect, so the measurement is not perfect (i. e., it has error)
The error in the measurement is related to the accuracy and the precision of the measurement

22. Accuracy and Precision
Accuracy – how close the measurement is to the “true” value (of course we have to know what the “true” value is)
Precision – is a measure of how closely individual measurements agree with one another.

23. Example: Accuracy and Precision

24. Equations for Precision and Accuracy
Percent Error
% Error = (True value-Calculated Value) X 100
True Value
You will have to find the % Error for most of your labs!