Final answer:
Elementary reactions are the basic steps in a series of chemical reactions. The different types include termolecular reactions and unimolecular reactions.
Step-by-step explanation:
Elementary reactions are the basic steps in a series of chemical reactions that occur in a stepwise fashion to convert reactants to products. They represent the progress of a reaction at the molecular level. A reaction mechanism is the sequence of elementary steps that make up an entire chemical reaction.
The different types of elementary reactions include:
- Termolecular reactions: These are elementary reactions involving three reactant species.
- Unimolecular reactions: These are elementary reactions involving a single reactant species.
It is important to note that these elementary reactions can be part of larger reaction mechanisms that involve multiple steps.