So then in order to figure out the complete number of valence electrons in our molecule, we just add 5 plus 4 plus 1.

那么接下来为了得到,这个分子中价电子的总个数，我们只需要将五加上四，再加上一。

麻省理工公开课 - 化学原理课程节选

All right, let's complete the cycle now, 3 the path number 3 here.

最后，来看路径。

麻省理工公开课 - 热力学与动力学课程节选

So we can completely describe an orbital with just using three quantum numbers, but we have this fourth quantum number that describes something about the electron that's required for now a complete description of the electron, and that's the idea of spin.

所以我们可以用３个,量子数完全刻画轨道，但我们有这第四个量子数,来完整的,描述电子，这就是自旋的概念。

麻省理工公开课 - 化学原理课程节选