Periodic Table


Atomic number: 9
Atomic weight: 18.9984032
Symbol: F
Group number: 12
Electronic configuration: [He].2s2.2p5


Fluorine is a Group 17 element. Fluorine is the most electronegative and reactive of all elements. It is a pale yellow, corrosive gas, which reacts with practically all organic and inorganic substances. Finely divided metals, glass, ceramics, carbon, and even water burn in fluorine with a bright flame.

Until World War 2, there was no commercial production of elemental fluorine. Atom bomb projects and nuclear energy applications made it necessary to produce large quantities of fluorine since isotopes of uranium can be separated through the gas diffusion of UF6. Reasonably safe handling techniques for fluorine are now available and one can transport liquid fluorine by the ton. Compounds of fluorine with noble gases such as xenon, radon, and krypton are known. Elemental fluorine and the fluoride ion (in quantity) are highly toxic.

General information

Discoveror: Henri Moissan
Date discovered: 1886
Discovered at: France
Meaning of name: From the Latin word "fluere" meaning "to flow"

Physical data

Standard state: gas at 298 K
Colour: pale yellow
Density of solid at ambient temperature/kg m-3: no data
Molar volume/cm3: 11.20

Radii /pm

Atomic: 42
Covalent (single bond):
Pauling radius for the ion [F]-: 136

Valence shell orbital radius maxima (Rmax)
orbital s p d f
radius40.638.1no datano data


Both values are quoted on the Pauling scale.

Pauling: 3.98
Allred Rochow: 4.10

Crystal Structure

structure: monoclinic

The following CrystalMaker image represents the solid state structure. For most elements, the most stable allotrope is illustrated. Try WebElements version 2 for interactive virtual reality and CHIME images.


Temperatures (/K)

melting point: 53.53
boiling point: 85.03

Enthalpies /kJ mol-1

fusion: 0.51
vaporization: 6.54

single bond enthalpies:
F-F F-Cl F-Br F-I F-F
155 249 249 278 158.75

Ionization enthalpies /kJ mol-1

Number Enthalpy


This section gives some data for naturally occurring isotopes.
Nominal mass Accurate mass % natural abundance
19F18.99840322 (15)100

Further Information

Copyright 1997 Mark Winter
Department of Chemistry at the University of Sheffield, Sheffield S3 7HF, England.

The current version of this document is at http://www.shef.ac.uk/~chem/web-elements-I/F.html