T

Transition State

Transition state: [A---B]‡ at top of energy barrier; ΔG‡ = activation energy
Quick Reference
Formula / NotationTransition state: [A---B]‡ at top of energy barrier; ΔG‡ = activation energy
Also Known AsActivated complex, transition state species, TS, saddle point

What is Transition State?

The highest-energy species along a reaction coordinate, occurring at the activation energy maximum. Unlike intermediates, transition states cannot be isolated. They involve partial bond breaking and forming. The transition state theory explains how activation energy relates to reaction rate.

Formula & Notation

Transition state: [A---B]‡ at top of energy barrier; ΔG‡ = activation energy

Other Names / Synonyms: Activated complex, transition state species, TS, saddle point

Properties & Characteristics

The transition state is the highest-energy, unstable configuration of reactants along the reaction coordinate as they transform into products. It represents the point at which bonds are simultaneously breaking and forming. Unlike intermediates, the transition state cannot be isolated. The activation energy (ΔG‡) is the energy difference between the transition state and the reactants.

Uses & Applications

Transition state theory is used to calculate and predict reaction rate constants. It guides the design of enzyme active sites and organocatalysts that stabilise specific transition states. Computational chemistry models transition state structures to develop better catalysts.

Safety Information

Transition states are theoretical constructs, but reactions with unstable or energetic transition states may produce reactive intermediates. Understanding transition state energetics helps identify conditions where reactions become uncontrolled.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Transition State
Formula Transition state: [A---B]‡ at top of energy barrier; ΔG‡ = activation energy
Synonyms Activated complex, transition state species, TS, saddle point

Frequently Asked Questions

The highest-energy species along a reaction coordinate, occurring at the activation energy maximum. Unlike intermediates, transition states cannot be isolated. They involve partial bond breaking and forming. The transition state theory explains how activation energy relates to reaction rate.

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