activation barrier

This term is a technical expression used primarily in chemistry and biochemistry to describe the energy threshold required to initiate a chemical reaction. It is closely related to the concept of activation energy, though the term barrier emphasizes the energetic obstacle that reactants must overcome to reach the transition state.

In a professional scientific context, the term is used to explain reaction kinetics and the efficacy of catalysts. A catalyst functions specifically by providing an alternative reaction pathway with a lower activation barrier, thereby increasing the reaction rate without being consumed in the process.