Chemical and Physical Changes

There are two types of change that matter can undergo:
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

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