This Demonstration considers the molecular orbitals for the diatomic molecules
. The conceptual relationship to the constituent atomic orbitals is shown in a schematic energy diagram. Antibonding MOs are shown in red. The bond order of a molecule is defined as the number of electrons occupying bonding MOs minus the number occupying antibonding MOs, all divided by 2, to coincide with the conventional chemical definition of single, double, and triple bonds. The molecules
have bond orders equal to 0, and exist only as weakly-associated van der Waals dimers.
also has bond order 0, but forms a weak chemical bond attributed to some 2s
hybridization. The "molecular data" checkbox brings up the ground state electron configuration and spectroscopic designation for each diatomic. The dissociation energy
is also given, showing an expected increase with bond order.