We're saying the probability of from the nucleus in some very thin shell that we describe by d r.

某一非常薄的壳层dr内,一个原子的概率,你想一个壳层时。

麻省理工公开课 - 化学原理课程节选

And here d, of course, can take the values from plus three down to minus three.

而d层，当然，能够包括从+3到-3的所有值。

麻省理工公开课 - 固态化学导论课程节选

s But it just turns out that the 4 s is so low in energy that it actually surpasses the 3 d, because we know the 3 d is going to be pretty high in terms of the three shell, and the 4 s is going to be the lowest interms of the 4 shell, and it turns out that we need to fill up the 4 s 4s before we fill in the 3 d.

但是结果是,能量较低,4s是第四层最低的，因为我们知道3d在第三层,是非常高的，4s是第四层,最低的，结果是我们在填充3d之前,需要先填充。

麻省理工公开课 - 化学原理课程节选