Transition state
In a chemical reaction, the transition state is the point where there is a maximum value of energy. This energy is called the activation energy. When two or more molecules are mixed, they will hit each other. If they hit with enough energy to go through the transition state, they will react and form new molecules. At the transition state, new bonds are formed while the old ones are broken. In a graph or a drawing, the transition state is often marked with the double dagger ‡ symbol.