Summary:
- Molecularity of a reaction is the number of molecules reacting in an elementary step.
- A unimolecular reaction is one in which only one reacting molecule participates in the reaction.
- Two reactant molecules collide with one another in a bimolecular reacted.
- Termolecular reactions are relatively rare because they involve the simultaneous collision of three molecules in the correct orientation, a rare event.
- Another reaction involves the conversion of ozone (O3) to oxygen (O2) with ultraviolet light.