The Physical Mechanism of the Chemical Bond

First the interplay of kinetic and potential energy via the uncertainty relation is described with the aid of a variational function for the ground state of the H atom. The H ion is used to illustrate the physical mechanism of the occurrence of the chemical bond. The formation of the chemical bond can be divided into three steps: 1. the quasi‐classical (electrostatic) interaction of the unchanged electronic charges of the separate atoms; 2. the interference of the atomic orbitals, which (in the case of positive interference) leads to a displacement of charge into the bonding region and to a decrease in the kinetic energy; 3. deformation of the molecular orbitals to restore the correct balance of kinetic and potential energy. In simple models, it is often sufficient to consider just the second step. A two‐electron bond is not fundamentally different from a one‐electron bond. In larger molecules it is possible to distinguish between long‐range and short‐range interatomic contributions to the chemical bond. If the former are small, i. e. in molecules with non‐polar bonds, a one‐electron molecular orbital theory can be justified. Finally, the possibility of describing molecules by localized bonds is discussed.