When the central atom is surrounded by five things, it has a trigonal bipyramidal geometry, which looks like two tetrahedrons fused at one base. Unlike the simpler geometries, there are three different bond angles in this molecule between different bonds: 90^o, 180^o and 120⁰.

Type	Bond Angle	Example	Lewis Structure
AX5: Trigonal Bipyramidal	90o, 120o, 180o	PCl5

If one of the bonded atoms is replaced by a lone pair, the molecule assumes a see-saw geometry, with a 90^o, 120^o and 180^o angles between the bonds. Removing two gives a t-shaped geometry, with 90^o and 180^o angles, and removing three gives a linear geometry, with 180^o angles.

Type	Bond Angle	Example	Lewis Structure
AX4E: See-Saw	90o, 120o, 180o	SF4
AX3E2: T-shaped	90o, 180o	ClF3
AX2E3: Linear	180o	SF4

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