So, let's write this one electron orbital approximation for berylium, that sounds like a pretty complicated question, but hopefully we know that it's not at all, 1s22s2 it's just 1 s 2, and then 2 s 2.
所以让我们写出,铍的单电子轨道近似，那听起来像是一个更为复杂的问题，但是希望我们知道它一点都不是，它仅仅是。
化学原理课程节选 : 麻省理工公开课