Key idea
Hund's rule
Hund’s rule describes the lowest-energy filling pattern within a set of degenerate orbitals: electrons occupy different orbitals with parallel spins before pairing, in the usual atomic model.
Hund's rule
The key idea
Hund’s rule describes the lowest-energy filling pattern within a set of degenerate orbitals: electrons occupy different orbitals with parallel spins before pairing, in the usual atomic model.
Why it matters
It helps explain ground-state electron configurations and magnetic behaviour, but it belongs to a broader quantum-mechanical energy picture.
A picture to remember
Key idea
Hund's rule
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Guided example
Hund's rule
Hund’s rule describes the lowest-energy filling pattern within a set of degenerate orbitals: electrons occupy different orbitals with parallel spins before pairing, in the usual atomic model.
Put it into practice
Hund's rule
Choose a concrete case linked to Hund's rule. Write down the known information, what you are trying to find, and the units. Then state the rule, model or trend you will use. If a calculation is involved, keep the units visible at every line; if it is conceptual, state what changes and what remains fixed.
Check your answer
A strong answer contains four things: the starting situation, the variable that changes, the direction or numerical result, and one check. The check can be a unit, an order of magnitude, a limiting case or a comparison with a familiar example.