The Great Chicken-and-Egg of Chemistry: Bonding vs. Stability Revisited

TL;DR

This paper critically examines the concept of chemical bonding, emphasizing its role as a derived descriptor rather than a fundamental physical entity, and discusses its implications for understanding chemical stability and causation.

Contribution

It revisits the logical foundations of bonding, clarifies its status as a state-dependent descriptor, and challenges traditional notions of causality in chemistry.

Findings

Bonding is not present in the molecular Hamiltonian.

Bonding correlates with stability but does not cause it.

Examples include QTAIM, NCI, and hydrogen bonding.

Abstract

The chemical bond is a central organizing concept in chemistry, yet it is absent from the molecular Hamiltonian and no "bond operator" exists. Bonding is therefore not a primitive physical entity but a derived descriptor emerging from the quantum state. The logical consequences of this observation are revisited. Statements such as "bonding stabilizes structure" when taken literally risk circular reasoning (petitio principii), whereby bonding is inferred from a stationary structure and then invoked as its cause. The same caution applies to concepts such as steric repulsion, which is also a derived descriptor. Bonding accompanies stable or metastable states and correlates with their properties without constituting their cause. Illustrative examples are drawn from QTAIM, non-covalent interaction (NCI) approach, protein structure, and hydrogen-hydrogen bonding. Causation, language, and the autonomy of chemistry are also briefly discussed. The aim is not at all to diminish the role of bonding, but to place it at the correct logical level, that is, as a powerful, state-dependent descriptor that organizes, classifies, and predicts chemical behavior without serving as its fundamental cause.