And when we talk about l it is a quantum number, so because it's a quantum number, we know that it can only have discreet values, it can't just be any value we want, it's very specific values.

当我们讲，l是一个量子数时，因为它是量子数，我们知道，它只能去分立的值，它不能取到所有的数，它取一些确定的数。

麻省理工公开课 - 化学原理课程节选