activation energy ( I know it is right because it is in my science book)

An exergonic reaction is activation energy (or energy of activation).

An endergonic reaction is essentially the opposite of an exergonic reaction.

Activation energy is the amount of energy that should be gained by potential reactants, for a reaction to occur. A reaction can be occurred by reducing the activation energy of the reaction or increasing the activation energy of the reactants. Activation energy should be added.

activation energy activation energy

That is called the activation energy or energy of activation (Ea).