Full configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d⁴ 5s¹
In the short form, [Kr] stands for the 36 electrons of krypton, the noble gas before niobium. Only the electrons after it are written out.
Orbital diagram
4p↑↓↑↓↑↓
4d↑↑↑↑
5s↑
Outer subshells only. Each box is an orbital; electrons fill singly first (Hund's rule), then pair up with opposite spins.
Why it's an exception
Niobium is in group 5, period 5, in the d-block. It has 5 unpaired electrons in the ground state, so the atom is paramagnetic.
Nearby elements
| Z | Element | Configuration |
|---|---|---|
| 38 | Strontium | [Kr] 5s² |
| 39 | Yttrium | [Kr] 4d¹ 5s² |
| 40 | Zirconium | [Kr] 4d² 5s² |
| 42 | Molybdenum | [Kr] 4d⁵ 5s¹ |
| 43 | Technetium | [Kr] 4d⁵ 5s² |
| 44 | Ruthenium | [Kr] 4d⁷ 5s¹ |
Questions students ask
What is the electronic configuration of niobium?
[Kr] 4d⁴ 5s¹, or in full, 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d⁴ 5s¹. Niobium has atomic number 41.
How many electrons are in each shell of niobium?
2, 8, 18, 12, 1 (K, L, M, N… shells in order).
How many unpaired electrons does niobium have?
5 in the ground state, so niobium atoms are paramagnetic.
Why is niobium an exception?
A half-filled or completely filled subshell is extra stable, so an electron moves to reach it.