Transition State Theory
Definition and meaning of Transition State Theory in chemistry.
Transition state theory is a framework that explains the reaction rates of elementary chemical reactions by assuming a special type of chemical equilibrium between reactants and activated transition state complexes.
In more detail
Developed primarily by Henry Eyring, this theory posits that as reactant molecules collide and react, they must pass through a temporary, high-energy structural configuration known as the transition state or activated complex. The overall rate of the chemical reaction is determined by the concentration of these activated complexes situated at the peak of the potential energy barrier, and the specific rate at which they break apart to form the final products. It provides a more detailed thermodynamic and statistical mechanical understanding of reaction kinetics compared to the older collision theory, which only considers collision frequency and kinetic energy.
Key facts
| Field | Physical Chemistry |
|---|---|
| Key Concept | Activated complex |
| Alternative Name | Activated-complex theory |
In the bimolecular nucleophilic substitution (SN2) reaction between a hydroxide ion and methyl chloride, the transition state involves a central carbon atom partially bonded to both the incoming hydroxide nucleophile and the departing chloride leaving group simultaneously.
Frequently asked questions
How does transition state theory differ from collision theory?
While collision theory focuses on the frequency of collisions with sufficient kinetic energy, transition state theory strictly considers the thermodynamic properties of the activated complex formed at the top of the energy barrier.