IB CHEMISTRY

2.2.4 VSEPR Model

Valence Shell Electron Pair Repulsion Theory.

Principle

Electron domains repel each other and orient themselves as far apart as possible.

Lone Pair - Lone Pair > Lone Pair - Bonding Pair > Bonding Pair - Bonding Pair

VSEPR Explorer

Bond Angle

109.5°

Yellow Lobes = Lone Pairs

Red Sphere = Central Atom

White Spheres = Bonded Atoms

Geometries (Up to 4 Domains)

DomainsLone PairsElectron GeometryMolecular GeometryAngle
20LinearLinear180°
30Trigonal PlanarTrigonal Planar120°
31Trigonal PlanarBent (V-shaped)<120°
40TetrahedralTetrahedral109.5°
41TetrahedralTrigonal Pyramidal<109.5°
42TetrahedralBent (V-shaped)<<109.5° (~104.5°)