activation energy

noun

, Chemistry.

1. the least amount of energy required to activate atoms or molecules to a state in which they can undergo a chemical reaction.

activation energy

/ ăk′tə-vā′shən /

1. 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.

Word History and Origins

Origin of activation energy¹

First recorded in 1920–25

Example Sentences

Just about everything in my life—from getting out of bed to exercising to writing to coaching to reading—required a significant amount of activation energy.

From Time

“Just like with a new fitness program, participants feel good after completing the workout, but it takes a lot of activation energy to start and hard work to get there,” Chen notes.

From TechCrunch