expanded octet

…Lewis terms, hypervalence requires the expansion of the octet to 10, 12, and even in some cases 16 electrons. Hypervalent compounds are very common and in general are no less stable than compounds that conform to the octet rule.

…of, without having to invoke octet expansion, by the distributed bonding effect of delocalized electrons. Consider SF₆, which according to Lewis’s theory needs to use two of its 3d orbitals in addition to its four 3s and 3p orbitals to accommodate six pairs of bonding electrons. In MO theory, the…