A molecular orbital (MO) is an orbital that extends over a whole molecule rather than belonging to a single atom, and is occupied by electrons that belong to the molecule as a whole. Molecular orbitals are formed by combining atomic orbitals from different atoms. They may be bonding, antibonding, or non-bonding, depending on how the atomic orbitals combine.

分子轨道(MO)是遍及整个分子、而不属于单个原子的轨道,其中的电子属于整个分子。分子轨道由不同原子的原子轨道组合而成。根据原子轨道组合方式的不同,它们可以是成键、反键或非键轨道。