Molecularity

The molecularity is the number of molecules that take part as reactants in an elementary process, that is, the sum of the molecules of each reactant before forming the activated complex to become the products.

It is a theoretical concept that indicates the number of individual particles that participate in an elementary step of the reaction mechanism.

In the elementary processes (steps) of the reaction mechanism, order of reaction and molecularity can coincide. There can be no elementary reactions with molecularity greater than 3 (Thermolecular).

Unimolecular process

AΔ Δ B+C{displaystyle Alongrightarrow B+C}

Bimolecular process

A+BΔ Δ C{displaystyle A+Blongrightarrow C}

Bimolecular process

2AΔ Δ F{displaystyle 2Alongrightarrow F}

Trimolecular Process (Thermolecular)

2A+BΔ Δ C{displaystyle 2A+Blongrightarrow C}