Additional examples of structures with lone pairs are illustrated in Figure 3-13.
Notice that the structures based on a trigonal bipyramidal arrangement of electron pairs
around a central atom always place any lone pairs in the equatorial plane, as in SF4,
BrF3, and XeF2. These are the shapes that minimize both lone pair-lone pair and lone
pair-bonding pair repulsions. The shapes are called teeter-totter or seesaw (SF4),
distorted T (BrF3), and linear (XeF2).