Iron Electron Configuration
Orbital diagram
- Valence electrons
- 8
- Unpaired electrons
- 4
- Block
- d-block
- Magnetism (atom)
- paramagnetic
Electrons per shell
| K (n = 1) | 2 |
|---|---|
| L (n = 2) | 8 |
| M (n = 3) | 14 |
| N (n = 4) | 2 |
Iron ion configurations
| Ion | Electrons | Configuration |
|---|---|---|
| Fe2+ | 24 | [Ar] 3d6 |
| Fe3+ | 23 | [Ar] 3d5 |
How to write it
Place 26 electrons into subshells in the Aufbau order (1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p), filling s with 2, p with 6, d with 10 and f with 14. Iron sits in period 4, group 8, in the d-block, so its last electron enters a d subshell. Replacing the inner electrons with the previous noble gas gives the shorthand [Ar] 3d6 4s2.
Try iron and its ions in the calculator, or see the full iron data sheet.
Iron electron configuration FAQ
What is the electron configuration of iron?
1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s². Shorthand (noble gas) notation: [Ar] 3d⁶ 4s².
What is the noble gas configuration of iron?
[Ar] 3d⁶ 4s². The bracket stands for the Ar core electrons.
How many valence electrons does iron have?
8 (2 outer s + 6 d electrons; 2 in the outermost shell).
How many unpaired electrons does iron have?
4 in the ground state, following Hund’s rule. An atom with unpaired electrons is paramagnetic.
What is the electron configuration of Fe2+?
[Ar] 3d⁶ (24 electrons). Transition metal cations lose their outer s electrons before d electrons.
What is the electron configuration of Fe3+?
[Ar] 3d⁵ (23 electrons). Transition metal cations lose their outer s electrons before d electrons.