1. Unit 1 – Chapter 3 Notes
Mr Nelson

2. The Properties of Matter
Matter: The “stuff” that makes up the universe
Has mass and volume
All matter is made up of tiny particles called atoms

3. Elements and Compounds
There are over 100 different kinds of atoms
We call these different types of atoms different elements
All matter is made up of different combinations of elements

4. Molecules A molecule is made of atoms that are “stuck” together
Smallest part of a compound that has properties of that compound
Can be the same atoms

5. Compounds
Compounds: substances made by bonding atoms together in specific ways.
Two or more different types of atoms bonded together
A compound has the same particles throughout

6. Pure Substances Pure substances always have a definite composition
Elements
Specific Compounds
They are not generic (Orange Juice)

7. Physical vs. Chemical Properties
Chemical Properties: examples are:
Rusting, not reacting, fermentation, combustion
You must perform a chemical reaction to test chemical properties (and then you change the substance!)

8. Physical vs. Chemical Properties
Physical properties: examples are:
Odor, color, volume, solid, liquid, or gas, density, melting point, boiling point
You can test physical properties without changing the substance

9. Intensive vs Extensive Properties
Depend on how much substance
Mass, length, volume
Intensive
Inherent quality of substance
Density, odor, color

10. Chemical and physical changes
Physical changes – don’t affect the composition of the substance
Involves physical properties
Solid  liquid  gas
Chemical changes – a given substance is changed to another substance
Silver tarnishing
Leaves growing from soil, water, and air

11. Which is which? Iron is melted Iron combines with oxygen to form rust
Wood burns in air
A rock is broken in to small pieces
Milk turns sour
Wax is melted
Wax catches on fire
A bee stings you and you swell up

12. Mixtures and Pure Substances
A mixture is something that has variable composition
Wood – varies depending on the tree it is cut from
Soda – contains lots of dissolved substances (CO2, sugar)
Air – contains lots of different substances in different amounts, depending on where you are.

13. Substances in the air N2 = 78.08% O2 = 20.95%
H2O = depends on humidity
Ar = 0.93%
CO2 = 0.033%
Ne = %
He = %

14. Compounds vs. Mixtures The air is not the same everywhere
Florida’s air is probably not the same as Death Valley’s air!

15. Gold
Pure gold is too soft and “bendy” (the scientific word is malleable) to be useful
We mix it with silver and copper to strengthen it
Mixtures of metals are called Alloys

16. Compounds vs. mixtures
Remember – a compound has particles that are ALL THE SAME
A mixture has different compounds/elements in different proportions
Is this an example of a mixture or a compound?

17. Pure substances A pure substance always has the same composition
Pure substances can be elements or compounds
Mixtures can be separated in to pure substances:
Two or more pure substances
Mixtures

18. Types of mixtures
Homogeneous mixtures: the mixture is the same throughout
Gatorade
Salt water
These are also called solutions
Heterogeneous mixtures: some regions have different properties than others (not uniformly mixed)
Sand in water
Dirt

19. Which is which? Gasoline A stream with gravel at the bottom
Maple syrup
Oxygen and helium in a scuba tank
Air
Brass
Copper metal
Sodium chloride (salt)

20. Law of Definite Proportions
Compounds are always composed of the same elements.
Table salt is always sodium chloride, otherwise it is something else
Example: A 58.5 gram sample of Table Salt is composed of 23.0g of Sodium.
What mass % is sodium & chlorine?

21. Law of Multiple Proportions
When different compounds are formed by the combination of the same elements the mass ratio of the two elements of the different compounds is a whole number.
Hydrogen and Oxygen – 2 compounds
H2O H2O2

22. Mass % of element in one compound compared to % mass of same element in a different compound is always a whole number ratio.

23. Law of Multiple Proportions
Example: Iron combines with oxygen in different ratios FeO & Fe2O3
In a 100g sample of each
In compound 1 Fe is 77.7g of the compound
In compound 2 Fe is 69.9g of the compound
Find the whole number ratio of the mass %’s?
Which compound is which? (Hint: definite prop)