IB ChemistryStructure 22.22.2.13
2.2.13
HL ONLY

Expanded Octet & Hybridization

Geometries for 5 and 6 electron domains.

5 Electron Domains

Lone Pairs Geometry Angles Example
0 Trigonal Bipyramidal 90°, 120°, 180° PCl₅
1 See-saw 90°, 120°, 180° SF₄
2 T-shaped 90°, 180° ClF₃
3 Linear 180° I₃⁻

6 Electron Domains

Lone Pairs Geometry Angles Example
0 Octahedral 90°, 180° SF₆
1 Square Pyramidal 90°, 180° BrF₅
2 Square Planar 90°, 180° XeF₄

Why can Period 3+ elements expand?

Atoms in Period 3 and beyond have empty d-orbitals available. These can participate in bonding, allowing more than 8 electrons around the central atom.

← 2.2.12 Benzene 2.2.14 Formal Charge →