A. Pauli exclusion principle
B. Aufbau principle
C. Hund's rule
D. Heisenberg uncertainty principle
Answer: Hund's rule
Which rule states that electrons will fill degenerate orbitals singly before pairing up?
Additional Information: Hund's rule states that electrons fill degenerate orbitals singly before pairing up to minimize electron repulsion.
Subjects: Atomic Structure, Chemistry