The study of the deltahedral structures of this element’s hydride clusters (10[1])motivated the development of polyhedral skeletal electron (10[1])pair theory. (10[1])Two banana-shaped bonds (10[3])appear (10[1])in a compound (10[2])consisting of two atoms (10[1])of this (10[1])element (-5[1])and six (10[1])hydrogen atoms; (10[1]-5[2])those bonds are three-center (-5[2])two-electron bonds. (-5[1])The hexagonal form (10[1])of this element’s (-5[1])nitride (-5[1])has a structure analogous (10[3])to graphene. (10[5]-5[1])With the halogens, (-5[2])this element forms trigonal (10[1])planar (-5[1])compounds (10[1]-5[2])that are (10[1])considered (10[2]-5[1])“electron-deficient,” (10[2]-5[1])such (10[1])as (10[1])a (10[1])trifluoride (10[3]0[1])that (10[3])violates (10[4]-5[1])the (10[1]-5[1])octet (10[1]-5[1])rule. (10[6]-5[1])For (10[1])10 (10[1])points, (10[1])name this (10[1])lightest (10[1])metalloid element (10[2]-5[2])with atomic number five, (10[16])symbolized (10[4])B. (10[4])■END■ (10[26]0[3])