Chemical Reactions

Chemical and Physical

Key Vocabulary

Precipitate: cause (a substance) to be deposited in solid form from a solution.

Exothermic: (of a reaction or process) accompanied by the release of heat.

Endothermic: (of a reaction or process) accompanied by or requiring the absorption of heat.

Physical Reactions

Physical change occurs when molecules are rearranged, but not chemically changed down the the molecular level. EXAMPLES: Boiling water, weathering rocks, dicing potatoes.

Chemical Reactions

Chemical change occurs when a change changes the chemical makeup of a substance. It breaks the bonds between atoms. EXAMPLES: oxidation, burning gasoline, bread rising.

What They Have in Common

Both change the appearance of the object. They both cause changes. And they both occur after a reaction.