Covalent Bond
Purely electrostatic attractions between ions are nondirectional, but with increasing covalent character the directional properties of valence orbitals become more important. Compounds between nonmetallic elements have predominantly covalent bonding and the structures will often be rationalized from the expected CN and bonding geometry of the atoms present. Thus in SiC both elements have tetrahedral coordination; in SiO2 silicon also forms, oxygen two bonds and four tetrahedral bonds with a nonlinear geometry.