9FFluorine18.9984031636[He] 2s² 2p⁵
diatomic nonmetal
Fluorine
Fluorine is a chemical element with symbol F and atomic number 9. It is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. As the most electronegative element, it is extremely reactive:almost all other elements, including some noble gases, form compounds with fluorine.
A stylized shell model. Electrons are quantum objects, not particles following these literal paths. Sizes and motion are illustrative.
Electrons by shell
Electron configuration
2s2
2p5
At a glance
- Atomic number
- 9
- Atomic mass
- 18.998403 u
- Phase
- Gas
- Density
- 1.696 g/L
- Melting point
- 53.48 K
- Boiling point
- 85.03 K
- First ionization energy
- 1,681 kJ/mol
- Electronegativity
- 3.98
- Electron affinity
- 328.1649 kJ/mol
- Molar heat capacity
- Unavailable
- Period
- 2
- Appearance
- Unavailable
Conditions and isotopes affect measured properties. Some properties of short-lived elements are predicted. Electronegativity uses the Pauling scale.
Keep exploring
Explore the stories, imagery, and reference data in more depth. Properties with no value in the reference are marked unavailable.