OK, then it says draw a single bond from each surrounding atom to the central atom, and subtract two valence electrons.

后将中心原子与其相邻原子之间,连上单键，然后减掉2个价电子。

麻省理工公开课 - 固态化学导论课程节选

Step three in our Lewis structure rules is to figure out how many electrons we would need in order for every single atom in our molecule to have a full valence shell.

路易斯结构规则的第三步是,找出让分子中每个原子的价壳层,都排满应该需要多少个价电子。

麻省理工公开课 - 化学原理课程节选

N 2 So any chemist should be able to just look at n 2 and know that it's a triple bond, but that's not something that we've learned how did to do yet, so let's go ahead and start a new topic that's going to allow us to have some sort of sense of what the valence electron configuration, which includes whether something's a single or double or a triple bond can be figured out for any given molecule.

任何一个化学家都应该能够仅仅通过看到2,就知道它有一个三键,但是我们还没学习如何做到这点，因此下面我们就开始进入一个新的主题,它将使我们能够有一定的认识,对于价电子的排布情况，包括可以对任何一个给定分子中的键是单键双键,还是三键作出判断。

麻省理工公开课 - 化学原理课程节选