自从知道分子是由原子组成,而原子是由带正电的核及带负电的核外电子组成后,便有分子中电荷分布的原子点电荷模型:即在分子中某些原子上带适量的正电荷,而在另一些原子上则带适量的负电荷。但是,随着人们对客观事物的进一步认识,和有了描述微观粒子运动的量子力学后,得知分子中电荷分布的实际情况要复杂得多:正电荷集中在各原子核上,而带负电的一部分内层电子虽仍围绕着原来的原子核运动,但另一部分原来各原子的外层价电子 Since we know that a molecule is made up of atoms and atoms are made up of positively charged nuclei and negatively charged extranuclear electrons, then there is an atomic point charge model of the charge distribution in the molecule: that is, some atoms in the molecule carry an appropriate amount of Positive charge, while in some other atoms with a suitable amount of negative charge. However, as people become more aware of objective things and have the quantum mechanics to describe the movement of microscopic particles, it is much more complicated to know the actual distribution of charge in a molecule: the positive charge is concentrated on each nucleus and the negative charge Part of the inner electron still revolves around the original nuclear movement, but the other part of the outer atoms of the outer valence electron