A reaction mechanism is the detailed description of how a chemical reaction takes place, step by step. Instead of just showing the starting materials and final products, it explains the individual stages where bonds break, new bonds form, and intermediate species appear and disappear.
- Each stage in the mechanism is called an elementary step.
- Temporary species that are made in one step and used up in another are called intermediates.
- The rate-determining step is the slowest step, which controls the overall speed of the reaction.
- The mechanism must agree with both the overall balanced reaction and the experimentally observed rate law.
In short, the reaction mechanism is like the “storyline” of a reaction — showing exactly how reactants transform into products.