Ruthenium Electron Configuration
★ Exception to the Aufbau order. Predicted 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d6 5s2; measured 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d7 5s1.
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) | 18 |
| N (n = 4) | 15 |
| O (n = 5) | 1 |
Ruthenium ion configurations
| Ion | Electrons | Configuration |
|---|---|---|
| Ru3+ | 41 | [Kr] 4d5 |
How to write it
Place 44 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. Ruthenium sits in period 5, 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 [Kr] 4d7 5s1.
Try ruthenium and its ions in the calculator, or see the full ruthenium data sheet.
Ruthenium electron configuration FAQ
What is the electron configuration of ruthenium?
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d⁷ 5s¹. Shorthand (noble gas) notation: [Kr] 4d⁷ 5s¹.
What is the noble gas configuration of ruthenium?
[Kr] 4d⁷ 5s¹. The bracket stands for the Kr core electrons.
Why is ruthenium’s electron configuration an exception?
The simple filling (Aufbau) order predicts 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d⁶ 5s², but the measured ground state is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d⁷ 5s¹. Shifting an electron gives a lower overall energy because the subshells involved are very close in energy.
How many valence electrons does ruthenium have?
8 (1 outer s + 7 d electrons; 1 in the outermost shell).
How many unpaired electrons does ruthenium have?
4 in the ground state, following Hund’s rule. An atom with unpaired electrons is paramagnetic.
What is the electron configuration of Ru3+?
[Kr] 4d⁵ (41 electrons). Transition metal cations lose their outer s electrons before d electrons.