Fluorine (F)
[He] 2s² 2p⁵. 1 unpaired electron, period 2, group 17, p block.
Element or ion
Type a symbol, a name or an atomic number, add a charge such as Fe3+ or Cl-, or tap an element in the table. Orbitals fill from m = −l up, spin +½ first.
FFluorine, Z = 9, 18.998 u
[He] 2s2 2p5
In full: 1s² 2s² 2p⁵
- Blockp block
- Period2
- Group17
- Valence7
- Unpaired1
- MagneticPara
Last electron 2p
- n2shell
- l1p subshell
- m0orbital
- s−½spin down
Step by step
- Fluorine has 9 electrons.
- Fill in (n + l) order: 1s² 2s² 2p⁵.
- Write the subshells in order of n: 1s² 2s² 2p⁵.
- Replace the helium core with [He]: [He] 2s² 2p⁵.
Fluorine (F): the numbers
| Atomic number | 9 |
|---|---|
| Atomic mass | 18.998 u |
| Period | 2 |
| Group | 17 |
| Block | p block |
| Valence electrons | 7 |
| Unpaired electrons | 1 |
| Magnetic | paramagnetic |
| Last electron | 2p: n = 2, l = 1, m = 0, s = −1/2 |
Fluorine (F): quick answers
What is the electronic configuration of fluorine?
Fluorine has 9 electrons: 1s² 2s² 2p⁵, or [He] 2s² 2p⁵ in short.
How many unpaired electrons does fluorine have?
Fluorine has 1 unpaired electron, so it is paramagnetic. Put one electron in each box of a subshell before pairing (Hund’s rule) to see them.
What are the quantum numbers of the last electron of fluorine?
The last electron goes into 2p: n = 2, l = 1, m = 0, s = −1/2. Orbitals fill from m = −l up, spin +½ first.