1. Lecture Physical/Chemical Change

2. Mixtures are created by: physically changing substances: salt/pepper Compounds are created by chemically changing substances: rust nail I. Physical change A. matter which is changed by only its appearance B. it can be changed back to the original form by physical means C. mixtures are examples of a physical change: they just appear/look different when in fact it is the same stuff all mixed up.

3. D. indicators: 1. size change (mass, volume) 2. shape change 3. phase change 4. dissolving 5. magnetism E. Key point: no bonds between atoms are broken or created F. demo: paper tearing

4. 2. Chemical change A. matter which is changed by rearranging its atomic makeup B. new substance created C. cannot be changed back to original form by physical means, only by chemical means D. Indicators 1. gas is formed (bubbles: careful: ?) 2. new odor 3. new color: not reversible! 4. heat released 5. light 6. sound 7. precipitate: careful ?

5. F. bonds are broken and/or are formed G. demo: burn paper: observations?