F
Fluorine
Element 9 · Halogen
Fluorine (F)
Fluorine is a pale yellow gas and the most reactive and most electronegative of all elements. It attacks almost every other substance.
- Halogen
- Period 2
- Group 17
- p-block
- gas at room temperature
Key properties
- Atomic mass
- 18.9984
- u
- Electron configuration
- [He] 2s2 2p5
- Melting point
- -219.6 °C
- 53.53 K
- Boiling point
- -188.1 °C
- 85.03 K
- Density
- 1.696 g/L
- Electronegativity
- 3.98
- Pauling
- Atomic radius
- 135 pm
- van der Waals
- 1st ionisation energy
- 17.423 eV
Compare with every element:Electronegativity chartAtomic radius chartIonisation energy chartDensity chart of the elementsMelting point chartElectron configuration chart
Did you know?
Notable facts about fluorine
- 01
Several chemists were injured or killed trying to isolate fluorine before Moissan succeeded; he won the 1906 Nobel Prize.
- 02
Fluorine reacts even with the noble gases xenon, krypton and radon.
- 03
Teflon’s non-stick surface comes from very strong carbon–fluorine bonds.
Applications
What is fluorine used for?
- Toothpaste and water fluoridation
- Teflon (PTFE) coatings
- Uranium enrichment (UF₆)
- Refrigerants
History
Discovery & name origin
Discovered by
Year
Where
France
Name origin
Latin fluere, “to flow” — from fluorite, used as a flux in metal smelting.
Atomic structure
Atomic properties
Atomic structure
Atomic properties
- Atomic number
- 9
- Atomic mass
- 18.9984 u
- Group
- 17
- Period
- 2
- Block
- p-block
- Electron configuration
- [He] 2s2 2p5
- Full configuration
- 1s2 2s2 2p5
- Electrons per shell
- 2, 7
- Electronegativity (Pauling)
- 3.98
- Electron affinity
- 3.339 eV
- Atomic radius (van der Waals)
- 135 pm
- Stable isotopes
- 1
Oxidation states
Highlighted: common oxidation states (-1).
Successive ionisation energies
Energy to remove each electron in turn (kJ/mol). Big jumps show where a new, inner shell begins.
- 1st1,681
- 2nd3,374.2
- 3rd6,050.4
- 4th8,407.7
- 5th11,022.7
- 6th15,164.1
- 7th17,868
- 8th92,038.1
Physical
Physical properties & colour
Physical
Physical properties & colour
- State at 20 °C
- Gas
- Melting point
- 53.53 K · -219.6 °C · -363.3 °F
- Boiling point
- 85.03 K · -188.1 °C · -306.6 °F
- Density
- 1.696 g/L
- Molar heat capacity
- —
- Appearance
- —
- CPK model colour
- Copied
The CPK colour is the convention used for this element’s atoms in molecular models.
FAQ
Fluorine questions
What is F on the periodic table?
F is the symbol for fluorine, element 9 on the periodic table. It sits in group 17, period 2, in the halogen category, and has an atomic mass of 18.9984.
What is the atomic number of fluorine?
Fluorine has atomic number 9, so every fluorine atom has 9 protons in its nucleus. Its symbol is F and its atomic mass is 18.9984.
Who discovered fluorine?
Fluorine was discovered by Henri Moissan in 1886 (France). The name comes from Latin fluere, “to flow” — from fluorite, used as a flux in metal smelting.
What is fluorine used for?
Fluorine is used for: toothpaste and water fluoridation; Teflon (PTFE) coatings; uranium enrichment (UF₆); refrigerants.
Is fluorine a metal?
No. Fluorine is classed as a halogen.
What is the electron configuration of fluorine?
The electron configuration of fluorine is [He] 2s2 2p5. Its 9 electrons are arranged in shells as 2, 7.