Full configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d⁹ 6s¹
In the short form, [Xe] stands for the 54 electrons of xenon, the noble gas before platinum. 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.
Why it's an exception
Platinum has 5d⁹ 6s¹ rather than 5d⁸ 6s², because of relativistic effects on the 6s orbital.
Configuration of platinum ions
| Ion | Configuration | Unpaired | Moment (BM) |
|---|---|---|---|
| Pt²⁺ | [Xe] 4f¹⁴ 5d⁸ | 2 | 2.83 |
| Pt⁴⁺ | [Xe] 4f¹⁴ 5d⁶ | 4 | 4.90 |
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 |
|---|---|---|
| 75 | Rhenium | [Xe] 4f¹⁴ 5d⁵ 6s² |
| 76 | Osmium | [Xe] 4f¹⁴ 5d⁶ 6s² |
| 77 | Iridium | [Xe] 4f¹⁴ 5d⁷ 6s² |
| 79 | Gold | [Xe] 4f¹⁴ 5d¹⁰ 6s¹ |
| 80 | Mercury | [Xe] 4f¹⁴ 5d¹⁰ 6s² |
| 81 | Thallium | [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p¹ |
Questions students ask
What is the electronic configuration of platinum?
[Xe] 4f¹⁴ 5d⁹ 6s¹, or in full, 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d⁹ 6s¹. Platinum has atomic number 78.
How many electrons are in each shell of platinum?
2, 8, 18, 32, 17, 1 (K, L, M, N… shells in order).
How many unpaired electrons does platinum have?
2 in the ground state, so platinum atoms are paramagnetic.
What is the electronic configuration of Pt²⁺?
[Xe] 4f¹⁴ 5d⁸, with 2 unpaired electrons.
Why is platinum an exception?
Platinum has 5d⁹ 6s¹ rather than 5d⁸ 6s², because of relativistic effects on the 6s orbital.