The study of the deltahedral structures of this element’s hydride clusters motivated the development of polyhedral skeletal electron pair theory. Two banana-shaped bonds appear in a compound (10[1])consisting of two atoms of this element and six hydrogen atoms; those bonds are three-center two-electron bonds. The hexagonal form of this element’s nitride has a structure analogous to graphene. (10[1]-5[1])With the halogens, this element forms trigonal planar (-5[1])compounds that are considered “electron-deficient,” such as a trifluoride (10[1])that (10[1])violates (10[1]-5[1])the octet rule. (10[1]-5[1])For 10 (10[1])points, name this lightest metalloid element with atomic number five, (10[2])symbolized (10[1])B. ■END■ (10[2])