KnowraPrincipal quantum numberLinked fromLinked fromThe 15 pages that link to Principal quantum number, each with the reason it gives.All 15Broader topic 3Related 11Compared with 1Atomic orbitalBroader topic: It identifies the shell and sets the main scale of an orbital.Electron shellBroader topic: It is the defining label shared by every electron in a shell.Hydrogen-like atomBroader topic: For a Coulomb-bound electron, it indexes the principal energy levels.