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Electron Pair Repulsion

Quick Reference
Also Known AsVSEPR (Valence Shell Electron Pair Repulsion), electron pair geometry

What is Electron Pair Repulsion?

The basis of VSEPR theory, which states that electron pairs around a central atom arrange themselves to minimize repulsion. Lone pairs repel more strongly than bonding pairs, influencing molecular geometry. This theory predicts the shapes of molecules.

Properties & Characteristics

Electron pair repulsion is the principle underlying VSEPR (Valence Shell Electron Pair Repulsion) theory: all electron pairs in the valence shell of a central atom repel each other and arrange themselves to minimise repulsion. Lone pairs repel more strongly than bonding pairs (LP-LP > LP-BP > BP-BP). This arrangement determines molecular geometry. For example: 4 BP → tetrahedral (109.5°); 3 BP + 1 LP → trigonal pyramidal; 2 BP + 2 LP → bent.

Uses & Applications

VSEPR is used to predict molecular shapes without detailed quantum mechanical calculations. It explains geometries of water (bent), ammonia (pyramidal), methane (tetrahedral), SF₆ (octahedral), and PCl₅ (trigonal bipyramidal), which determine polarity, reactivity, and biological activity.

Safety Information

Molecular geometry determines toxicity and biological action. Knowing the shape of toxic molecules (nerve agents are tetrahedral at phosphorus, fitting enzyme active sites) aids in designing antidotes and protective equipment.

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

Key Facts

Term Electron Pair Repulsion
Synonyms VSEPR (Valence Shell Electron Pair Repulsion), electron pair geometry

Frequently Asked Questions

The basis of VSEPR theory, which states that electron pairs around a central atom arrange themselves to minimize repulsion. Lone pairs repel more strongly than bonding pairs, influencing molecular geometry. This theory predicts the shapes of molecules.

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