Full configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁶ 7s²
In the short form, [Rn] stands for the 86 electrons of radon, the noble gas before radium. 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
Radium is in group 2, period 7, in the s-block. It has 0 unpaired electrons in the ground state, so the atom is diamagnetic.
Configuration of radium ions
| Ion | Configuration | Unpaired | Moment (BM) |
|---|---|---|---|
| Ra²⁺ | [Rn] | 0 | 0.00 |
Moment is the spin-only magnetic moment μ = √(n(n + 2)) Bohr magnetons, where n is the number of unpaired electrons.
Nearby elements
| Z | Element | Configuration |
|---|---|---|
| 85 | Astatine | [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁵ |
| 86 | Radon | [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁶ |
| 87 | Francium | [Rn] 7s¹ |
| 89 | Actinium | [Rn] 6d¹ 7s² |
| 90 | Thorium | [Rn] 6d² 7s² |
| 91 | Protactinium | [Rn] 5f² 6d¹ 7s² |
Questions students ask
What is the electronic configuration of radium?
[Rn] 7s², or in full, 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁶ 7s². Radium has atomic number 88.
How many electrons are in each shell of radium?
2, 8, 18, 32, 18, 8, 2 (K, L, M, N… shells in order).
How many unpaired electrons does radium have?
0 in the ground state, so radium atoms are diamagnetic.
What is the electronic configuration of Ra²⁺?
[Rn], with 0 unpaired electrons.