MechanismThe order of events in going from reactantto product. An “event” is a breaking of a bond, the making of a bond, or the simultaneous making and breaking of a bond. Hammonds Postulate If two states, as for example, a transition state(TS) and an unstable intermediate, occurconsecutively during a reaction process andhave nearly the same energy content, theirinterconversion will involve only a smallreorganization of the molecular structures. 。