A chemical reaction in which a compound is broken down (decomposed) into simpler substances

A reaction in which the composition of a substance is changed

Number placed in front of a formula to show how many moles of that substance

Chemical reaction in which a compound is broken down into simpler substances (analysis) AB  A + B

Molecule containing two identical atoms

Chemical reaction in which ions exchange places AB + CD  AD + BD

Chemical formula with coefficients in lowest terms

Chemical reaction that absorbs heat Heat is on the reactant (left) side of the equation Products have higher potential energy than reactants

Chemical reaction that releases heat Heat is on the product (right) side of the equation Products have less potential energy than reactants

Symbols and subscripts that represent the composition of a substance

Actual ratio of atoms in a substance (not necessarily lowest terms)

Smallest unit of a covalently bonded substance

Change that does not alter the chemical properties of a substance

Covalently bonded group of atoms that have a net charge and behave as a single unit

Substance formed in a chemical reaction On the right side of the equation

Information that cannot be counted or measured

Information that can be counted or measured

Starting substance in a reaction On the left side of the equation

Reaction in which a more reactive element replaces a less reactive element in a compound AB + C  AC + B

Number written after a symbol that tells how many of that substance

A one, two, or three (experimental only), letter designation of an element

Chemical reaction in which two or more substances chemically combine to form one substance A + B  AB

Sum of atomic masses of all atoms

Formula mass expressed in g rather than in u

6.02 x particles Number atoms present on g of carbon-12

Percent of each element compared to the total mass of the compound