The Madelung Rules

I’ve been thinking about chemistry lately. I’m always amazed by how far we can get in the study of multi-electron atoms using ideas from the hydrogen atom, which has just one electron.

If we ignore the electron’s spin and special relativity, and use just Schrödinger’s equation, the hydrogen atom is exactly solvable—and a key part of any thorough introduction to quantum mechanics. So I’ll zip through that material now, saying just enough to introduce the ‘Madelung rules’, which are two incredib...