Chemistry Chemical Reactions Study Guide Definitions

Law of Conservation of Mass

Mass cannot be created or destroyed only take up a new form

Physical Change

Change in a substance that doesn’t change its identity

Chemical Change/Chemical Reaction

Change of a substance into another substance when substances collide with enough energy that new bonds are formed between atoms

Five Signs of a Chemical Reactions

Energy change, color change, odor change, gas release, and creation of a solid

Reactants

Starting substances

Products

Ending substances

Coefficient

Number of each substances needed

Subscript

Number of each element needed

Synthesis

Two or more reactants combine to form a new compound

Decomposition

One reactant produces two or more simpler compounds

Combustion

When a substance reacts with oxygen

Single Replacement

When one element replaces an element like it in a compound

Double Replacement

When the ions of two compounds exchange places to form two new compounds