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).