Atomic number 9
Fluorine
Halogen
Quick facts
- Atomic mass
- 18.998
- Group
- 17
- Period
- 2
- State (STP)
- gas
- Electronegativity
- 3.98
- Common ox. states
- -1
Properties
Electron configuration
[He] 2s² 2p⁵
- Ionization energy
- 1681.0 kJ/mol
- Electron affinity
- 328.0 kJ/mol
- Melting point
- 53.48 K (-219.7 °C)
- Boiling point
- 85.03 K (-188.1 °C)
How it bonds
Fluorine is the most electronegative element. It forms exactly one bond — single, terminal, never a double — and keeps 3 lone pairs. Bonds to fluorine are short and strong; the C–F bond is one of the strongest in organic chemistry. Watch for the trap: fluorine never has a positive oxidation state. Period.