Electron Configuration of Beryllium (Be)
Beryllium (Be, Z = 4) has the electron configuration [He] 2s^2, filling 2 shells with 2, 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 Beryllium page is one click away.
Beryllium: every subshell, one by one
The table below unpacks [He] 2s^2 line by line, so you can watch Beryllium's 4 electrons take their seats in order of increasing energy.
| Subshell | Electrons | Total so far |
|---|---|---|
| [He] | 0 | 2 |
| 2s | 2 | 4 |
Electrons per shell (K, L, M…)
Grouped by principal quantum number instead of subshell, Beryllium carries 2 in shell 1, 2 in shell 2. 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 4 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 Beryllium that gives [He] 2s^2.
Students also ask
How many electron shells does Beryllium have?
Beryllium is in period 2, so its electrons occupy 2 shells, holding 2, 2 electrons respectively.
How many valence electrons does Beryllium have?
Its outermost shell holds 2 electrons, so Beryllium has 2 valence electrons that take part in bonding.
What is the noble-gas shorthand for Beryllium?
The shorthand form is exactly [He] 2s^2.