For a chemical reaction to occur, the bonds within the reactants must be broken and new bonds must be formed between the atoms to make the products. The energy required to break the bonds is called the Activation energy Ea. It is the minimum energy required for the reaction to take place.Reactions with low activation energies take place rapidly because the energy needed to break the bonds is readily available from the surroundingsReactions with very high activation energies will take place very slowly or not at all because the activation energy acts as an energy barrier to the reaction.A reaction profile diagram shows the relative energies of reactants and product and the activation energy.