1. Physical and Chemical Changes

2. Physical Changes
A change that alters the form or appearance, but does not make the material into a new substance.
The properties change, but the particles are still the same.
Examples
Tearing paper
Phase changes
Crushing a can

3. Chemical Changes
A change in matter that produces a substance with new properties.
Both the physical and chemical properties of the substance will be changed.

4. Common Chemical Changes
Burning/Combustion
Rusting
Tarnishing
Digestion
Photosynthesis

5. Chemical or Physical Change?
A piece of metal is bent
A bracelet turns green
A plant makes its own food
An apple rots
Hair is cut

6. Chemical Reactions
A process in which a substance undergoes a chemical change.
If a chemical reaction happens, a chemical change has occurred.

7. Types of Chemical Reactions
Exothermic Reaction:
Heat EXITS
It feels warm
Temperature increases
Examples: burning wood, “hot hands”

8. Types of Chemical Reactions
Endothermic Reaction:
Heat ENTERS
Feels cold
Temperature decreases
Example: cold pack

9. Law of Conservation of Matter
Atoms can rearrange during a chemical reaction but the amount that you start with is the amount that you end with.
“Nothing is created nor destroyed”