The screening (shielding) effect is the reduction in an electron's attraction to the nucleus caused by the repulsion of other electrons, especially the inner electrons that lie between it and the nucleus. As a result, an outer electron experiences less than the full nuclear charge. The effect is quantified by the screening constant and leads to the idea of the effective nuclear charge.

屏蔽效应是因其他电子(尤其是位于某电子与核之间的内层电子)的排斥作用,使该电子受核吸引减弱的现象。其结果是外层电子所感受到的核电荷小于全部核电荷。该效应用屏蔽常数来量化,并引出有效核电荷的概念。