Electron Configuration of Radium (Ra)
Radium (Ra, Z = 88) has the electron configuration [Rn] 7s^2, filling 7 shells with 2, 8, 18, 32, 18, 8, 2 electrons.
This is the fast lane: one page, one fact, zero digressions. Read the quick answer, check the table, and if your exam needs the full derivation, the sections below walk through it step by step — in Bangla and English, like every page here. Need the whole picture instead — history, characteristics, uses, exam questions? The full Radium page is one click away.
Radium: every subshell, one by one
The table below unpacks [Rn] 7s^2 line by line, so you can watch Radium's 88 electrons take their seats in order of increasing energy.
| Subshell | Electrons | Total so far |
|---|---|---|
| [Rn] | 0 | 86 |
| 7s | 2 | 88 |
Electrons per shell (K, L, M…)
Grouped by principal quantum number instead of subshell, Radium carries 2 in shell 1, 8 in shell 2, 18 in shell 3, 32 in shell 4, 18 in shell 5, 8 in shell 6, 2 in shell 7. The outermost shell holds 2 electrons — the ones that do all the bonding.
How to derive it yourself
Follow the aufbau order (1s → 2s → 2p → 3s → 3p → 4s → 3d → …), pouring 88 electrons into orbitals of capacity 2 (s), 6 (p), 10 (d) and 14 (f) until none remain. Write the filled inner shells as the nearest noble-gas core — for Radium that gives [Rn] 7s^2.
Students also ask
How many electron shells does Radium have?
Radium is in period 7, so its electrons occupy 7 shells, holding 2, 8, 18, 32, 18, 8, 2 electrons respectively.
How many valence electrons does Radium have?
Its outermost shell holds 2 electrons, so Radium has 2 valence electrons that take part in bonding.
What is the noble-gas shorthand for Radium?
The shorthand form is exactly [Rn] 7s^2.