| Term | Definition |
| reactant | a substance that undergoes chemical change |
| product | a substance that is the result of a chemical change |
| chemical energy | the energy stored within atoms and molecules that can be release when a substance reacts |
| exothermic reaction | a reaction that transfer energy from the reactants ot the surrounding as heat |
| endothermic reaction | a reaction in which energy is transferred to the reactants as heat from the surrounding |
| synthesis reaction | a reaction of at least 2 substances that forms a new, more complex compound |
| decomposition reaction | a reaction in which one compound breaks down into at least 2 products |
| electrolysis | the decomposition of a compound bye electricity |
| combustion reaction | a reaction in which a compound and oxygen burn |
| single replacement reaction | a reaction in which atoms of one element take the place of atoms of another element in a compound |
| double replacement reaction | a reaction in which a gas, a solid precipitate or a molecular compound is formed from the apparent exchange of ions between 2 compouds |
| reduction/oxidation reaction | a reaction that occurs when electrons are transferred from one reactant to another |
| radicals | the fragments of molecules that have at least one electron available for bonding |
| chemical equation | an equation that uses chemcial formulas and symbols to show the reactants and products in a chemical reaction |
| catalyst | a substance that changes the rate of a chemical reactions without being consumed |
| enzyme | a protein that speeds up a specific biochemical reaction |
| substrate | the specific substance affected by an enzyme |
| equilibrium | the state in which a chemical reaction and its reverse occur at the same time and at the same rate |