activation energy
noun Chemistry.
the least amount of energy required to activate atoms or molecules to a state in which they can undergo a chemical reaction.
Origin of activation energy
First recorded in 1920–25
Words nearby activation energy
Scientific definitions for activation energy
activation energy
[ ăk′tə-vā′shən ]
The least amount of energy needed for a chemical reaction to take place. Some elements and compounds react together naturally just by being close to each other, and their activation energy is zero. Others will react together only after a certain amount of energy is added to them. Striking a match on the side of a matchbox, for example, provides the activation energy (in the form of heat produced by friction) necessary for the chemicals in the match to ignite. Activation energy is usually expressed in terms of joules per mole of reactants.