The energy needed to destabilize existing chemical bonds and start a chemical reaction is called

If all chemical reactions that release free energy tend to occur spontaneously,why haven't all such reactions already occurred? One reason is that most reactions require an input of energy to get started.Before it is possible to form new chemical bonds,even bonds that contain less energy,it is first necessary to break the existing bonds,and that takes energy.The extra energy required to destabilize existing chemical bonds and initiate a chemical reaction is called activation energy.