1. CHANGES

2. PHYSICAL PROPERTIES
Physical property- characteristics of a material that can be observed without changing the identity of the substances in the material.
These include color, shape, size, density, melting point, and boiling point

3. Appearance- Physical description of a substance
Appearance- Physical description of a substance. (color, shape, size, density)
Behavior- How a substance acts. (magnetism, viscosity, ductility)
Observations- Start and end with the same substance

4. PHYSICAL CHANGE
Physical change- Change in a substance’s size, shape, or state of matter.
Substances do not change identity when it undergoes a physical change.

5. PHYSICAL CHANGES EXAMPLES
Biting
Melting
cutting

6. More Examples breaking a glass haircut adding chocolate squeezing
syrup to
ice cream
squeezing
a wet sponge

7. CHEMICAL PROPERTIES
Chemical property- characteristic of a substance indicating that it can change chemically. (flammability, light sensitivity)

8. Chemical Change
Chemical Change- When one substance changes to another substance a chemical change has occurred.
Some indicated by temperature change, color change, noticeable smell, gas production or formation of a precipitate
Others occur slowly. – rust

9. CHEMICAL CHANGES EXAMPLES
SALIVA, STOMACH ACID, ENZYMES (chemicals which speed up reactions)
Rust/Tarnishing
FIRE-burning

10. EVIDENCE OF
CHEMICAL CHANGES

11. WEATHERING Weathering- involves both chemical and physical changes.
Physical- ex: big rocks split
into smaller ones, streams carry
rocks from one place to another
Chemical-
ex: occur in rocks when
calcium carbonate in limestone
changes to calcium hydrogen
carbonate due to acid rain

12. Energy in Reactions

13. Bonding and Energy Energy is required to break chemical bonds.
Energy is released when chemical bonds are formed.

14. Chemical reactions can also be categorized into two types
Endothermic
Reactions
Exothermic
Reactions

15. Endothermic
Reactions

16. Sucks in the heat
Turns cold
Absorbs energy - heat

17. Endothermic (in-heat)
Reactions absorb heat by absorbing energy
Sometimes called endergonic

18. Endothermic
Temperature of the products may be less than temperature of reactants
This type of reaction produces a decrease in temperature

19. Endothermic
Examples :
Baking soda and vinegar
Instant cold packs

21. Exothermic
Reactions

22. Releases energy - heat

23. Exothermic (out-heat)
Reactions that produce heat by releasing energy
Sometimes called exergonic

24. Exothermic
Temperature of products is usually greater than temperature of reactants
This type of reaction produces an increase in temperature

25. Exothermic Examples : Hot hands Bunsen Burner-lit Candle
Combustion in car engine

27. Why isn’t freezing water an endothermic reaction?