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; (10[1])those bonds are three-center two-electron bonds. The hexagonal form of this element’s nitride has a structure analogous to graphene. (10[1])With the halogens, this element forms trigonal (10[1])planar compounds (-5[1])that are (10[1])considered (10[1])“electron-deficient,” such as a trifluoride (10[1])that (10[1])violates the octet (-5[1])rule. For 10 points, (10[1])name this lightest metalloid element with atomic number five, symbolized B. ■END■ (10[2]0[1])