The Octet Rule Revisited: A Quantum-Continuum Framework for Chemical Bonding

Abstract

The octet rule is ubiquitously taught as a universal principle of chemical stability, yet it is fundamentally a pedagogical approximation that breaks down across vast regions of chemical space. Hypervalent molecules (e.g., SF₆, PCl₅), electron-deficient systems (e.g., BF₃), transition-metal complexes, and metallic clusters all violate the rule in systematic and predictable ways. Despite this, no unified framework has reconciled these deviations with the underlying quantum-mechanical continuum of electronic interactions. Here, we propose a fully modern quantum-continuum interpretation of chemical bonding based on electron-density topology, multi-center bonding models, and the interplay between orbital energetics and electron correlation. This framework demonstrates that “octet violations’’ are not anomalies but natural consequences of delocalization, symmetry, and energy minimization in many-electron systems. By replacing the rigid octet paradigm with a continuous, energy-driven model, we resolve the apparent contradictions between introductory rules and real chemical behavior.

Keywords

Octet rule; hypervalent molecules; electron deficiency; quantum continuum model; QTAIM; ELF; multi-center bonding; chemical bonding theory.