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How to use Electron Configuration Calculator
Enter an element name, symbol or atomic number to see its ground-state electron configuration and orbital diagram.
- Type an element (iron, Fe or 26) or choose one from the list.
- Read the full configuration, the noble-gas shorthand and electrons per shell.
- Check the orbital diagram; elements whose real configuration differs from the filling rule are flagged.
Questions
What is the aufbau (Madelung) rule?
Electrons fill subshells in order of increasing n + l, and for equal n + l, lower n first: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p and so on.
Why are chromium and copper exceptions?
Half-filled and filled d subshells are especially stable, so chromium is [Ar] 3d5 4s1 and copper is [Ar] 3d10 4s1 rather than the predicted 3d4 4s2 and 3d9 4s2. The calculator uses measured ground states for these exceptions.
Are superheavy element configurations measured?
No. For elements 104 and above, configurations are predictions from the filling rule and are labelled as predicted.