Practice question · Fill in the blanks
Complete the statement of the three filling rules.
The ______ principle fills the lowest-energy orbital first, the ______ principle limits each orbital to two electrons, and ______ rule spreads electrons singly across degenerate orbitals before pairing.
Word bank: Aufbau · Pauli exclusion · Hund's · Heisenberg
Hints
- One rule is about order, one about capacity, one about spreading out.
- Heisenberg gave the uncertainty principle, which is not a filling rule.
Show the answer
The Aufbau principle fills the lowest-energy orbital first, the Pauli exclusion principle limits each orbital to two electrons, and Hund's rule spreads electrons singly across degenerate orbitals before pairing.
Why
Aufbau sets the order, Pauli sets the capacity, and Hund governs how degenerate orbitals share electrons. Heisenberg’s uncertainty principle is unrelated to filling.
Practise Orbitals, Quantum Numbers and Electron Configuration
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