Illustrated Glossary of Organic Chemistry

Exergonic: A process such as a chemical reaction in which the Gibbs free energy (G) of the products is smaller than the Gibbs free energy of the reactants (i.e., ΔG < 0). Work (energy) is released into the surroundings as the reaction proceeds. Such processes are thermodynamically spontaneous (i.e., K_eq > 0).

Energy profile for a concerted exergonic reaction.