An intermediate or transitional structure formed during the course of a reaction. Activated complex. An activated complex is a temporary and unstable arrangement of atoms that forms at the peak of a chemical reaction's energy barrier.
Imagine you are moving to a new house, and you find yourself in the middle of packing up your old home and setting up the new one. This in-between stage, where you’re neither fully settled in the old place nor the new one, is similar to the activated complex in a chemical reaction. Just as the transitional phase of moving represents a momentary state between two stable homes, the activated complex is a temporary, high-energy state that forms between reactants and products during a reaction, bridging the gap from one stable state to another.
