1. Physical & Chemical Changes

2. Physical Changes
Physical changes are changes that alter the size, shape, location or physical state of a substance but not its chemical state.

3. Don’t Use Dem Big Words Physical State- Substance- Solid Liquid Gas
Plasma
Substance-
Stuff… something… the item you are working with

4. Physical Change A change that affects one or more physical properties.
The substance is still the same substance
Example: Breaking a pencil or a piece of chalk.

5. Physical Change Examples
Freezing water
Dissolving sugar
Bending metal
Mixing oil & vinegar
Melting butter
Most of these changes be undone?

6. So What Does That All Mean?
Ok… here’s the deal…
If the thing is still the same thing after it has been changed…
It’s a Physical Change.
Example… Boiling water
Boiling Water becomes
Water vapor
Water = water

7. Here’s An Example…
A physical change in a substance doesn't change what the substance is.
cutting paper –
physical change in the shape and size of the paper.
It is still paper!!!!!!

8. What Other Changes are Physical?
Cutting
Tearing
Shredding
Grinding
Shrinking
Enlarging
Change in Phase
Relocating
Dissolving
Rotating
Molding (shaping)

9. Chemical Changes
Chemical changes are changes that alter the chemical make up of the substance being changed.

10. Chemical Change
A change that occurs when one or more substances are changed into entirely new substances with different properties.
Example: Baking a cake

11. Basically What You’re Telling Me Is…
If you end up with a chemical or chemicals that you did not start with,
It is a chemical change!!!!!!!

12. Here’s An Example… Burning anything…
Once something burns, it can not burn again…
Burn a piece of wood and what do you have?
Ash… not wood. Ash cannot be burned again. It is a new substance!!!

13. Another Example Is… Eating…
Now eating can change food both physically and chemically.
Chewing is Physical but…
Once your spit touches the food chemicals in the saliva begin to change the food chemically.

14. Signs That A Chemical Change Has Occurred
Creation of a gas (bubbles)
Temperature Change
Formation of a Precipitate
Color Change
Change in Odor

15. Chemical Change Examples
Soured milk
Effervescent tablets
Burning gases
Rusting metal
Can most of these changes be undone?

16. Review
Classify each of the following properties as either physical or chemical properties:
reacts with water
Boils at 100 degrees celcius
is blue
fizzes when combined with vinegar.
What are three clues that indicate a chemical change might be taking place?

17. Physical and Chemical Changes Quiz …True or False?
With a physical change, no new substance is formed.  
With a chemical change, a chemical reaction occurs.
With a physical change, energy is either given off or absorbed.
A chemical change can be easily reversed.
Eating food can be considered both physical and chemical changes.

18. Physical and Chemical Changes Quiz…Answers!
With a physical change, no new substance is formed.  
With a chemical change, a chemical reaction occurs.
A chemical change can be easily reversed.
Eating food can be considered both physical and chemical changes.
TRUE
TRUE
FALSE
TRUE