Full configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹ 4s²
In the short form, [Ar] stands for the 18 electrons of argon, the noble gas before scandium. Only the electrons after it are written out.
Orbital diagram
Outer subshells only. Each box is an orbital; electrons fill singly first (Hund's rule), then pair up with opposite spins.
What the configuration tells you
Scandium is the first transition element: its 21st electron goes into 3d after 4s is full.
Configuration of scandium ions
| Ion | Configuration | Unpaired | Moment (BM) |
|---|---|---|---|
| Sc³⁺ | [Ar] | 0 | 0.00 |
Moment is the spin-only magnetic moment μ = √(n(n + 2)) Bohr magnetons, where n is the number of unpaired electrons. Positive ions lose electrons from the outermost shell first, so transition metals lose their 4s or 5s electrons before d.
Nearby elements
| Z | Element | Configuration |
|---|---|---|
| 18 | Argon | [Ne] 3s² 3p⁶ |
| 19 | Potassium | [Ar] 4s¹ |
| 20 | Calcium | [Ar] 4s² |
| 22 | Titanium | [Ar] 3d² 4s² |
| 23 | Vanadium | [Ar] 3d³ 4s² |
| 24 | Chromium | [Ar] 3d⁵ 4s¹ |
Questions students ask
What is the electronic configuration of scandium?
[Ar] 3d¹ 4s², or in full, 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹ 4s². Scandium has atomic number 21.
How many electrons are in each shell of scandium?
2, 8, 9, 2 (K, L, M, N… shells in order).
How many unpaired electrons does scandium have?
1 in the ground state, so scandium atoms are paramagnetic.
What is the electronic configuration of Sc³⁺?
[Ar], with 0 unpaired electrons.