Chemical bonding and the role of node-induced electron confinement

The chemical bond is the cornerstone of chemistry, providing a conceptual framework to understand and predict the behavior of molecules in complex systems. However, the fundamental origin of chemical bonding remains controversial, and has been responsible for fierce debate over the past century. Here we present a unified theory of bonding, using a separation of electron delocalization effects from orbital relaxation to identify four mechanisms – node-induced electron confinement, Pauli repulsion, orbital contraction and polarization – that each modulate kinetic energy during bond formation. Through analysis of a series of archetypal bonds, we show that electron delocalization is not the universal driving force for bonding. Instead, an exquisite balance of delocalizing and localizing effects are dictated simply by atomic electron configurations, nodal structure and electronegativities. The utility of this unified bonding theory is demonstrated by its application to explain observed trends in bond strengths throughout the periodic table, including main group and transition metal elements.