How does an antibonding orbital compare to its corresponding atomic orbitals?

An antibonding orbital is formed when atomic orbitals combine in such a way that there is a node between the nuclei, resulting in a region of destructive interference. This leads to a situation where the electron density is pulled away from the region between the two atomic nuclei, a position of lower stability. As a result of this destabilizing effect, antibonding orbitals possess higher energy than the corresponding atomic orbitals from which they are derived.

The increase in energy is due to the fact that occupying an antibonding orbital can weaken or even negate the stabilizing interactions that characterize bonding orbitals. Therefore, when electrons occupy these higher-energy levels, they are generally less effectively engaged in bonding interactions, which can make the molecule more reactive. This behavior highlights the fundamental concepts of molecular orbital theory, whereby the energies of the resulting molecular orbitals are directly influenced by their bonding or antibonding character.