Triangular bipyramidal molecular shape

In any molecule in which there are no nonbonding pairs around the central atom, the molecular shape is the same as the molecular geometry. Thus, to use the examples from Table 6.2, all three two-substituent molecules have both a linear geometry and a linear shape. Both BH3 and H2CO have a triangular planar shape, CH4 has a tetrahedral shape, PF5 a triangular bipyramidal shape, and SF6 a square bipyramidal shape. 

Using this reasoning, we can predict that an AX4E molecule (that is, a molecule in which the central atom A is coordinated to four other atoms X and to one nonbonding electron pair) such as SF4 will have a see-saw shape substitution of more nonbonding pairs for bonded atoms reduces the triangular bipyramid coordination to even simpler molecular shapes, as shown below. (See the examples on the next page.)... 

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