Unit 7: Describing Matter.
Bell Ringer:
Take 4 sheets of paper
Make a foldable

Unit 7: Describing Matter.
Make Foldable to learn chemical,
physical properties, and the four signs of
a chemical change! 
You may use device OR textbook pages
43-51 to help
Unit 7: Describing Matter.
Examples of Physical Changes
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Tearing up your paper
Crushing a can
Freezing water into ice
Bending a paper clip
Dissolving salt in water
Cutting your hair
Unit 7: Describing Matter.
Examples of Chemical Changes
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Your car rusts
Burning wood
Glow sticks
Baking a cake
Food spoils
Sodium reacts with water – BOOM!
Unit 7: Describing Matter.
4 Signs of Chemical Changes:
• Unexpected color change
• Gas released
• production of light, sound, odor or heat.
• A precipitate forms
Unit 7: Describing Matter.
Precipitate: a solid formed in a solution
Unit 7: Describing Matter.
Law of Conservation of Mass
Mass is neither created nor destroyed in a
chemical reaction.
Example: Burning a piece of paper. It seems
that the mass shrinks as the paper burns.
Unit 7: Describing Matter.
Demo mystery powders
Unit 7: Describing Matter. Bell Ringer.
 What is the Law of Conservation of mass?
Give an example
 What are four signs of a chemical change?
Unit 7: Describing Matter.
Remember... Mixtures:
Combination of two or more
substances that are NOT
chemically combined.
Unit 7: Describing Matter.
Ways to Separate Mixtures
Physically
Unit 7: Describing Matter.
Ways to Separate Mixtures
Distillation: based on boiling point
Unit 7: Describing Matter.
Ways to Separate Mixtures
Magnet: for elements like iron and aluminum
Unit 7: Describing Matter.
Ways to Separate Mixtures
Centrifuge
Unit 7: Describing Matter.
Separating Mixtures Lab