1. 6th Grade Matter and Energy
Unit 1 Lesson 3 Physical and Chemical Changes

2. Physical changes of matter
Unit 1 Lesson 3 Physical and Chemical Changes
A physical change is a change that affects one or more physical properties of a substance.
Physical properties - appearance, shape, size, state of matter.… what else?
Do not change identity of substance
Good physical changes song -
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3. What are some ways you could cause a physical change?

4. Physical Change Physical changes might be caused by: Grinding Cutting
Crushing
Bending
Breaking
Heating/cooling
(change in phase)
squishing

5. Physical Change
Evidence that a physical change has occurred might include:
Change in shape
Change in form
Change in size
Change in phase (This is always a physical change!)
Physical changes are usually reversible

6. A chemical change is the process by which a substance changes into entirely new substances.
Not the same as chemical properties
For example:
BURNING = CHEMICAL change
FLAMMABILITY = chemical property
Chemical changes are often influenced by temperature.
Higher temperatures often mean faster chemical reactions.
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7. Chemical change Examples of chemical changes include: Burning Rusting
Tarnishing
Decomposing
Polymerization

8. Chemical change – Chemical reactions
There are 5 signs of a chemical reaction - evidence that a chemical change has occurred.
Chemical Changes – Crash course Kids

9. Evidence of Chemical change: 1. formation of a solid
this is also called “precipitation”.
The solid formed is a “precipitate”

10. Evidence of Chemical change 2. Production of a gas
A chemical reaction has happened when a gas is given off (with the exception of a phase change).

11. Evidence of Chemical change 3. Change in color
When two chemicals react, look for a change in the color.

12. Evidence of Chemical change 4. Change in odor
Sometimes, the first clue for a chemical change is the odor.

13. Evidence of Chemical change: 5. Energy is given off or absorbed
Indications include:
the temperature of the system goes up or down,
light, sound or electricity is given off or used

14. A chemical reaction that releases energy in the form of heat is called exothermic.
Heat comes OUT
Exo = out
Thermic = heat
It will feel HOT.
Do #12, p. 41

15. How can you tell a chemical change has happened?
Unit 1 Lesson 3 Physical and Chemical Changes
How can you tell a chemical change has happened?
Will heating the water in this beaker cause a physical or chemical change?
Physical and chemical changes rap -
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16. The law of conservation of mass states that in ordinary chemical and physical changes, mass is not created or destroyed. It is only transformed into different substances.
Vacation or Conservation (Of Mass): Crash Course Kids #
AND THEN (LEGO) Block Party: Crash Course Kids #
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17. Physical changes are reversible and follow the law of conservation of mass.
Mass is conserved during chemical changes. The mass of the starting materials is the same as the mass of the end products.
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18. French chemist Antoine Lavoisier studied chemical changes in which substances appeared to gain or lose mass.
Lavoisier completed experiments in sealed bulbs to show conservation of mass during a reaction.
Antoine Lavoisier - conservation of mass
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