sentence2_structure: Aufbau principle<>gives<>the order of electron filling in an atom$$$the order of electron<>filling<>in an atom
sentence1: 4 Be able to explain why the energy levels in multielectron atoms differ from the levels in the hydrogen-like atom 5 Be able to state and apply the Pauli Exclusion Principle, Hund's Rule, and the Aufbau Principle.
sentence2: Aufbau principle gives the order of electron filling in an atom.
question: What gives the order of electron filling in an atom?