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

We'll start up a shell and we'll try it. All right, we'll just get out of what we were doing here.

我们开一个shell然后试试，先退出现在的这个来。

麻省理工公开课 - 计算机科学及编程导论课程节选

So there are two electron configurations in the n equals one shell, if we follow according to the selection rules that we spelled out last day.

如果根据上次课,我们阐明的原子光谱选择定则，我们就会知道在n等于1的那一层,有两种电子图像构型。

麻省理工公开课 - 固态化学导论课程节选

s But it just turns out that the 4 s is so low in energy that it actually surpasses the 3 d, because we know the 3 d is going to be pretty high in terms of the three shell, and the 4 s is going to be the lowest interms of the 4 shell, and it turns out that we need to fill up the 4 s 4s before we fill in the 3 d.

但是结果是,能量较低,4s是第四层最低的，因为我们知道3d在第三层,是非常高的，4s是第四层,最低的，结果是我们在填充3d之前,需要先填充。

麻省理工公开课 - 化学原理课程节选