A pure (nonpolar) covalent bond is a bond in which two atoms share the bonding electrons equally, so that there is no separation of charge. This occurs when the two atoms have the same electronegativity, as in a bond between identical atoms. The Cl–Cl bond in Cl₂ is nonpolar, in contrast to a polar covalent bond, where sharing is unequal.

纯(非极性)共价键是两个原子均等共享成键电子、因而没有电荷分离的键。当两原子电负性相同时(如相同原子之间的键)便会如此。Cl₂ 中的 Cl–Cl 键是非极性的;与之相对的是共享不均等的极性共价键。