Originally posted by ChessPraxisAufbau is not a personal name it is "building up" so it's Aubau-principle.
Aufbau's Principle states that the orbitals are filled in the increasing order of their
energies (in the ground state). Following the (n + l) rule of Aufbau's principle, the orbitals
in the increasing order of energy are arranged as
1s ƒ¬ 2s ƒ¬ 2p ƒ¬ 3s ƒ¬ 3p ƒ¬ 4s ƒ¬ 3d ƒ¬ 4p ƒ¬ 5s ƒ¬ 4d ƒ¬ 5p
Be sensible.