| Term | Definition |
| energy | the ability to do work |
| calorimeter | a device used to measure the change in temperature while a reaction takes place |
| heat of fusion | the heat absorbed by one mole of substance when it melts |
| heat of vaporization | heat absorbed by one mole of substance when it boils |
| kinetic energy | the energy of moving particles |
| potential energy | the energy contained in chemical bonds |
| entropy | a measure of the disorder of a system |
| system | the reaction that we are studying |
| surroundings | everything outside the system |
| enthalpy | the heat content of a system at constant pressure |
| specific heat | the heat needed to raise the temperature of one gram of a substance by one degree Celsius |
| endothermic | describes a reaction that absorbs energy from the surroundings |
| exothermic | describes a reaction that releases energy to the surroundings |
| Joule | the SI unit of energy and heat |
| Kelvin | the SI unit of temperature |
| temperature | a measure of the kinetic energy of a substance |
| activation energy | the energy needed to make a reaction occur |
| catalyst | a substance that increases the rate of a reaction |
| inhibitor | a substance that decreases the rate of a reaction |
| activated complex | a temporary, unstable arrangement of molecules |