I've got two states here, three states here, two here, I need four, and if I can come up with these bonds, four, by the Hund rule I'd fill them like this.

我们已经有2个状态在这里，3个在这里，2个在这里，我需要4个，如果我能想到这些键，四个，通过洪特规则，我们就能像这样排布。

麻省理工公开课 - 固态化学导论课程节选