1. Physical and Chemical Changes

2. Concept of Change Change - the act of altering a substance
Changes can be physical or chemical
When considering what TYPE of change has occurred, ask yourself…
“Did the identity change?”
“Can I separate it?”

3. Physical Change
Physical change - a change that occurs that does not change the identity of the substance and can be separated.
Examples:
Tearing paper
Phase Changes like Melting,
Freezing, Boiling

4. Chemical Changes
Chemical change - a change that occurs causing the identity of the substance to change and cannot be separated.
Examples:
Burning paper
Digesting food
A chemical change is also called a chemical reaction

5. Chemical Changes Indicators of a chemical change: Evolution of light
Evolution of heat
Evolution of a gas
Color change
Formation of a Precipitate - a solid that forms when two liquids react with each other. Precipitate Video -

6. Possible Exceptions Not all color changes are chemical reactions…
When you mix water and Kool-Aid the color changes. But is it a chemical change?
Why? How do you know?
What are some other exceptions?

7. Is it Physical or Chemical?
Change
Physical
Chemical
Melting cheese
Burning wood
Baking cookies
Wadding up paper
Bicycle rusting

8. Think-Pair-Share
Look at the real-world examples on the back of the notes.
Think (1 min) – Answer individually
Pair (2 min) – Get with a partner and discuss your answers
Share (3 min) – Go over whole class

9. Snowball Fight
On the paper and write an example of a change from the chart.
Crumple and wad up the paper into a “snow”ball.
When I say so, throw the snowball at someone else in the room.
Open up a snowball near you and decide if the example is Physical or Chemical and write your name on it!
Crumple it up again and throw it one more time. Write Agree or Disagree and your name again.
Put it in the Apple Tray.