So the 3 s 1, or any of the other electrons that are in the outer-most shell, those are what we call our valence electrons, and those are where all the excitement happens.

它们是经常发生激发情况的,那也是我们所看到，我们称之为价电子，它们是经常发生激发情况的。

麻省理工公开课 - 化学原理课程节选