Elementary Reaction Definition

Elementary Reaction Definition Elementary Reaction Definition An elementary reaction is a chemical reaction where reactants form products in a single step with a single transition state. Elementary reactions may combine to form complex or nonelementary reactions. Elementary Reaction Examples Types of elementary reactions include: Unimolecular Reaction - a molecule rearranges itself, forming one or more products A → products examples: radioactive decay, cis-trans isomerization, racemization, ring opening, thermal decomposition Bimolecular Reaction - two particles collide to form one or more products. Bimolecular reactions are second-order reactions, where the rate of the chemical reaction depends on the concentration of the two chemical species that are the reactants. This type of reaction is common in organic chemistry. A A → products A B → products examples: nucleophilic substitution Termolecular Reaction - three particles collide at once and react with each other. Termolecular reactions are uncommon because its unlikely three reactants will simultaneously collide, under the right condition, to result in a chemical reaction. This type of reaction is characterized by: A A A → products A A B → products A B C → products Sources Gillespie, D.T. (2009). A diffusional bimolecular propensity function. The Journal of Chemical Physics  131, 164109.IUPAC. (1997). Compendium of Chemical Terminology, 2nd ed. (the Gold Book).