Periodic table / Halogens
9Fluorine
Fluorine is a halogen in group 17, period 2. At 25 °C it is a gas.
- Symbol
- F
- Atomic number
- 9 protons in the nucleus
- Standard atomic weight
- 18.998 ± 0.001
- Electron configuration
- [He] 2s2 2p5
- Electrons in each shell
- 2, 7
- Group, period, block
- 17, 2, p
- Family
- Halogens
- State at 25 °C
- gas
- Electronegativity
- 3.98 (Pauling scale)
- First ionisation energy
- 1681 kJ/mol (17.42282 eV)
Where these numbers come from
Atomic weight: IUPAC CIAAW, abridged standard atomic weights 2024. Electron configuration and ionisation energy: NIST Atomic Spectra Database. Family, state and electronegativity: PubChem. See Sources. Melting points, boiling points and densities are left out for now: published values differ between sources, and we will add them once each has been checked.