Answer:
Pauli exclusion principle
Step-by-step explanation:
Pauli's exclusion principle speaks to the quantum numbers assigned to an electron to describe it's general position and movement. Two electrons can occupy the same energy level (which is described by the first quantum number-the principal quantum number), the orbital angular momentum quantum number (represented by the second number) and magnetic quantum number. electrons that have the same value for all three numbers will have different spins. one will have positive a half while the other has negative a half. Therefore they will never have the same complement of quantum numbers