1. Physical and Chemical Changes

2. Physical Changes The appearance of a substance may have
changed BUT the bonds holding the atoms
together in molecules and ions have not been
broken and NO new bonds have been made.

3. Examples of Physical Changes
All changes in state
Dissolving
Cutting
Mixing
Note: Physical changes “tend” to be easy to reverse
You Tube Changes in State video
Youtube Dissolving video

4. Chemical Changes
Produces new substances with new properties (may or may not be noticeable)...NEW matter!
New bonds are formed while others are broken

5. Chemical Changes
Chemical equations can be written for all chemical changes.
For example the rusting of iron:
4Fe + 3O2 = 2Fe2O3
(Start with Reactants) (Produce Products)

6. Examples of Chemical Change
Rusting
Burning, combustion
Fruit ripening
Youtube Tomato decomposition video

7. Evidence of a Chemical Change
Heat, light or sound is produced or consumed
Gas bubbles are formed
A precipitate is formed
Colour change occurs
Difficult to reverse
Youtube Exothermic Reaction video
Youtube Exothermic Reaction video 2
Youtube Gas (CO2) Bubble formation video
Youtube Yellow precipitate formation video
Youtube Colour Change Reactions Video
Youtube Oscillating Iodine Clock Reaction