1) Chemical
2) Physical
Chemical Change
Any change that results in the formation of new chemical substances.
Key Words: reacts, forms, rusts, decomposes, digests, burns, forms, releases a gas, acid, cook
Ex:
- gasoline burning - produces water vapor and CO2
- eggs cooking - proteins uncoil and coil into a new form
- bread rising - yeast converts carbohydrates into CO2 gas
- milk souring - lactic acid is produced
- suntanning - vitamin D and melanin are produced
Physical Change
Any change that doesn't affect the internal structure of molecules. Any change that does not result in the formation of a new substance.
Key Words: cut, break, any phase change (melt, boil, condense, etc) , dissolve
Ex.
- whipping egg whites - air is forced into the fluid, no new substance is produced
- magnetising a compass needle - realigns groups of iron atoms, no new product is produced
- boiling water - heats water, changes its state, does not produce a new product
- dissolving sugar in water - sugar molecules disperse within the water, the individual sugar molecules are unchanged
- dicing potatoes - separates molecules, but you still have potatoes
Websites:
This website is a quiz on physical and chemical changes.
This website is a short review and a quiz.
This website discusses physical and chemical changes in depth and has links to other content areas of matter.
