1. Chemical and Physical Changes

2. Physical Changes
Changes that do not affect the nature or the characteristic properties of a substance
Ex. Breaking glass, phase changes

3. 1. Chanes of State
Phase change is a transformation from one state to another.

4. Energy in Phase Changes

5. Phase changes & Particle Model
Phase change don’t affect characteristic properties
Only the forces of attraction change
Particles don’t change= “same”

6. Energy in phase changes
Absorbs energy:
liquid water + energy water
vapour
Releases energy
liquid water ice + energy

7. 2. Dissolution
Creation of a solution by a solute dissolving in a solvent.
Solutes may:
Release energy
-temp. increases

8. Absorb Energy:
- temp. decreases

9. 3. Deformation
Means changing the shape of a material.

10. Chemical Changes
Changes that transform the nature and characteristic properties of a substance
Ex. Burning wood, cooking food,
Human body:
- cellular respiration
- digestion of food

11. Signs of a chemical change
Change of colour
Greater changes of heat
Generation of Light
Release of a Gas
Formation of a Precipitate (a solid material forms in a liquid)

12. 1. Synthesis
Formation of a complex molecule from atoms or simpler molecules
Ex. 2H H2O + energy

13. Ex. Photsynthesis
- plants transform radiant energy into chemical energy(2.45 p. 54)

14. 2. Decomposition
Transformation of complex molecules into simpler molecules or atoms.
Ex. Electrolysis
2H2O + electrical energy H

15. Digestion is a form of decomposition

16. 3. Oxidation
Chemical reaction involving oxygen or a substance that has similar properties to oxygen.
Slow- rusting of metals release energy
Rapid- combustion of fuels, very fast

17. Ex. Oxidation of Copper
2 Cu O CuO

18. Cellular respiration

19. 4. Precipitation Ex. Enzymes produce Precipitation in milk to
Formation of a solid that is less soluble, or not soluble, following the mixture of two solutions.
Ex. Enzymes produce
Precipitation in milk to
Produce cheese

20. Ex. Which product is the precipitate?
Symbols: (g) = gas, (l) = liquid (s) = solid, (aq) = solution water