Fluorine (F): Electron Configuration, Properties and Uses
Fluorine (F): Electron Configuration, Properties and Uses
Electron configuration [He] 2s2 2p5 · group 17 · period 2 · Ar 18.998
Fluorine data
- Atomic number
- 9
- Relative atomic mass
- 18.998
- Group
- 17
- Period
- 2
- Block
- p
- Category
- Halogen
- Electron configuration
- [He] 2s2 2p5
- Full configuration
- 1s2 2s2 2p5
- Electrons per shell
- 2, 7 (K L)
- Valence electrons
- 7
- Electronegativity (Pauling)
- 3.98
- First ionisation energy
- 17.423 eV
- Atomic radius (van der Waals)
- 135 pm
- State at room temperature
- Gas
- Melting point
- −220 °C
- Boiling point
- −188 °C
- Density
- 1.696 g/L (0 °C, 1 atm)
- Common oxidation states
- −1
- Discovered
- 1670
Source: PubChem (NIH, accessed 13 Nov 2026); atomic mass: IUPAC standard atomic weight.
Electron shell diagram
K 2 · L 7
Orbital diagram (outer electrons)
About fluorine
Fluorine is a chemical element with the symbol F and atomic number 9. It is a halogen in group 17, period 2, p-block. The element was discovered in 1670. At room temperature fluorine is a gas that is heavier than air (1.696 g/L) and liquefies at −188 °C.
Fluorine electron configuration
The electron configuration of fluorine is 1s2 2s2 2p5, or in short [He] 2s2 2p5. Its electrons occupy 2 shells: K = 2, L = 7. Fluorine has 7 valence electrons in the L shell (2s2 2p5), which is why it sits in group 17. In ionic compounds fluorine gains electrons to fill its outer shell: F− = [Ne] (like neon).
Filling order: 1s2(2) → 2s2(4) → 2p5(9)
Uses of fluorine
The main uses of fluorine include fluoride toothpaste, PTFE (Teflon), refrigerants, uranium enrichment (UF6) and lithium battery electrolyte salt (LiPF6). For research and analysis you can browse fluoride compounds in the AMI Scientific catalogue.
Safety
Fluorine gas is highly toxic and corrosive. Hydrofluoric acid (HF) penetrates skin and attacks bone, so it needs special handling. Always read the safety data sheet (SDS) before working with a chemical.
Other elements in group 17
Frequently asked questions
What is the electron configuration of fluorine?
The electron configuration of fluorine (F, atomic number 9) is 1s2 2s2 2p5, or [He] 2s2 2p5 in short. By shell: 2, 7.
How many valence electrons does fluorine have?
Fluorine has 7 valence electrons.
Which group and period is fluorine in?
Fluorine is in group 17, period 2, p-block.
What is the atomic mass of fluorine?
The relative atomic mass of fluorine is 18.998. Use it to calculate molar mass with the molar mass calculator.
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