Molecular orbital theory is a chemical model that describes the electronic structure of molecules by combining the atomic orbitals (AOs) of individual atoms to form new molecular orbitals (MOs). When atoms approach each other to form a chemical bond, the existing AOs mathematically overlap and combine. This linear combination of atomic orbitals results in a set of new orbitals that span the entire molecule, which are the molecular orbitals. These MOs possess specific energy levels and spatial orientations, determining how electrons are distributed within the chemical species and thus predicting the bonding characteristics, stability, and electronic properties of the molecule.