So what we know is that these 3 d orbitals are higher in energy than 4 s orbitals, so I've written the energy of the orbital here for potassium and for calcium.

我们所知道的是,3d轨道能量,比4s轨道能量高，所以我写出了,钾和钙的轨道能量。

麻省理工公开课 - 化学原理课程节选