VSEPR Model

Valence-shell electron-pair repulsion (VSEPR) is a model used to describe molecular geometry that can be summed up as electrons repel each other. Since electrons surrounding a central atom are either lone pairs or involved in bonds, this model predicts that they will repel each other and put as much radial distance as they can between them.

VSEPR molecular models

Groups
of
electrons		 Bonding
electon
groups		 Lone
pair
electrons		 Shape Example
2 2 0 linear BeCl2
3 3 0

trigonal
planar

 BF3
2 1 bent NO2–
4 4 0 tetrahedral NH4+
3 1 trigonal
pyramidal		 NH3
2 2 bent NH2–
5 5 0 trigonal
bipyramidal		 PCl5
4 1 see-saw SF4
3 2 T-shaped ICl3
2 3 linear I3–
6 6 0 octahedral IF6+
5 1 square
pyramidal		 IF5
4 2 square
planar		 ICl4–