So what that means is that we're limited in any atom to having two electrons per orbital, right, because for any orbital we can either have a spin up electron, a spin down electron, or both.

这意味着在一个原子内,每个轨道上可以有两个电子，对吧，因为对任何轨道,我们可以有自旋向上或者自选向下或者两者都有。

麻省理工公开课 - 化学原理课程节选