Electron Configuration of Fluorine (F)
Fluorine (F, Z = 9) has the electron configuration [He] 2s^2 2p^5, filling 2 shells with 2, 7 electrons.
Looking for Fluorine's electron configuration without wading through a whole chapter? Here is the direct answer first, then the tables and derivations examiners want to see. Every number on this page comes from the same engine that powers the interactive table. Need the whole picture instead — history, characteristics, uses, exam questions? The full Fluorine page is one click away.
Fluorine: every subshell, one by one
Read the configuration like a receipt: each line is one subshell, and the running total climbs exactly to 9 electrons — never one more, never one less.
| Subshell | Electrons | Total so far |
|---|---|---|
| [He] | 0 | 2 |
| 2s | 2 | 4 |
| 2p | 5 | 9 |
Electrons per shell (K, L, M…)
Grouped by principal quantum number instead of subshell, Fluorine carries 2 in shell 1, 7 in shell 2. The outermost shell holds 7 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 9 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 Fluorine that gives [He] 2s^2 2p^5.
Students also ask
How many electron shells does Fluorine have?
Fluorine is in period 2, so its electrons occupy 2 shells, holding 2, 7 electrons respectively.
How many valence electrons does Fluorine have?
Its outermost shell holds 7 electrons, so Fluorine has 7 valence electrons that take part in bonding.
What is the noble-gas shorthand for Fluorine?
The shorthand form is exactly [He] 2s^2 2p^5.