9
F
Fluorine
18.998403163
Fluorine (F)
HalogenGroup 17Period 2p-block-block
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.
Latin name: Fluorum
Atomic Number
9
Atomic Mass
18.998403163 g/mol
Phase (STP)
Gas
Electron Config.
[He] 2s² 2p⁵
General
SymbolF
Atomic Number9
Atomic Mass18.998403163 g/mol
CategoryHalogen
Group17
Period2
Blockp-block
Electron Configuration[He] 2s² 2p⁵
Valence Electrons7
ColourPale yellow gas
CAS NumberCAS7782-41-4
Physical Properties
Phase (STP)Gas
Density0.001696 g/cm³
Melting Point-219.62°C · -363.32°F · 53.53 K
Boiling Point-188.12°C · -306.62°F · 85.03 K
Atomic Properties
Atomic Radius42 pm
Covalent Radius57 pm
Van der Waals Radius147 pm
Electronegativity3.98 Pauling
Ionization Energy1681 kJ/mol
Electron Affinity328 kJ/mol
Oxidation States-1
Ion ChargeF⁻
Electromagnetic
Electrical TypeInsulator
Abundance
In Universe0.0040%
In Sun0.000004%
In Earth's Crust5.8500%
In Oceans0.0001%
In Humans0.3700%
In Meteorites0.8700%
Discovery & History
Discovery Year1886
Discovered ByHenri Moissan
Named ByHumphry Davy
Isotopes of Fluorine
| Isotope | Abundance | Half-life | Decay |
|---|---|---|---|
| F-19 | 100% | Stable | — |