The document summarizes the particle theory of matter. It states that all matter is made up of tiny particles that are always in motion. There are attractive forces between particles that get stronger when particles are closer together. Matter exists in two categories - pure substances that are either elements or compounds containing only one type of particle, and mixtures that contain two or more pure substances that are either homogeneous solutions or heterogeneous mixtures where the parts can be easily seen.

1. The Particle Theory
Chapter 2

2. The Particle Theory
More than 2000 years ago, a Greek
philosopher Democritus suggested that
matter was made of tiny particles too
small to be seen.
He thought if you kept cutting a substance
into smaller and smaller pieces, you would
find the building blocks of matter.

3. 4 Principles of the Particle Theory
1. All matter is made of tiny particles.
2. All particles of one substance are the same.
- Different substances are made of
different particles.
3. The particles are always moving.
- The more energy the particles have, the
faster they move.
4. There are attractive forces between
particles.
- These forces are stronger when the
particles are closer together.

4.  Theparticle theory helps to explain two
categories of substances that are
encountered in chemistry.

5. Two Categories of Substances
Category 1: Pure Substances
- contains only one kind of particle
- Types: elements and compounds
Category 2: Mixtures
- contains two or more different pure substances
- Types: homogeneous and heterogeneous mixtures

6. Category 1: Pure Substances
Type 1: Elements
– pure substances that cannot be broken down
into simpler substances
- Examples: think Periodic table (oxygen,
hydrogen)
Type 2: Compounds
– pure substances that contain two or more
elements
- Examples: Water (H2O), sugar (C6H12O6)

7. Category 2: Mixtures
Type 1: Homogeneous (also known as solutions)
– may be made up of solids, liquids or gases
- this mixture is uniform (the same) throughout
- Examples: air, alloys, kool aid, white vinegar,
orange juice without the pulp
Type 2: Heterogeneous
– see each part easily, separated physically
- this mixture is not uniform throughout
- Examples: pizza, garbage, beach sand,
vegetable soup

8. How to Classify Mixtures
 When two pure substances are mixed
together, they may mix smoothly or unevenly.
 If the substances mix well with one another,
the mixture is called a solution.
 If the particles don’t mix well together then we
have a heterogeneous mixture.

9. Classify the Following
 Salt and water
 solution
 Pizza
 heterogeneous mixture
 Garbage
 heterogeneous mixture
 Air
 solution

10. Atoms and Molecules
 Atoms
- each atom is made of one type of element
- scientists now call the particles in the particle theory atoms
- the periodic table of elements has 118 elements
 Molecules
- contains two or more atoms joined together in combinations
- Ex. C4H8 – contains 4 carbon atoms and 8 hydrogen atoms

11. Guess the Molecule
I have 2 hydrogen atoms
 I have 1 oxygen atom
 I am water

12. Guess the Molecule
 I have 10 hydrogen atoms
 I have 2 oxygen atoms
 I have 7 carbon atoms
 I have 4 nitrogen atoms
 I am desired in the morning but
avoid me in the evening
 Cola drinks have contain me
 I am what makes coffee
special
 I am caffeine

13. Guess the Molecule
 I have 6 hydrogen atoms
 I have 6 oxygen atoms
 I have 6 carbon atoms
 Everybody needs me
 I will help keep colds away
 You can get me by eating
oranges
 I am vitamin C

14. Guess the Molecule
 I have 8 hydrogen atoms
 I have 4 oxygen atoms
 I have 9 carbon atoms
 I am used quite often by
teachers, usually in pairs
 I am white in color
 You need water when you use
me
 I will make you feel better
 I am aspirin