Valence Shell Electron Pair Repulsion Theory

VSEPR theory proposes that the geometric arrangement of terminal atoms, or groups of atoms about a central atom in a covalent compound, or charged ion, is determined solely by the repulsions between electron pairs present in the valence shell of the central atom.

The number of electron pairs around the central atom can be determined by writing the Lewis structure for the molecule. The geometry of the molecule depends on the number of bonding groups (pairs of electrons) and the number of nonbonding electrons on the central atom.

The five important electron-pair geometries which we discussed in class were;

Electron-Pair Geometry


Trigonal Planar



Trigonal Bipyramidal