Image of Fluorine
Image courtesy of Mark Winter

Fluorine is the most reactive and electronegative element. It reacts with almost all compounds, organic and inorganic.


Fluorine is a pale yellow, corrosive gas


Fluorine was first identified by Scheele in 1771. It was not isolated until 1886 when Henri Moissan electrolysed Potassium Fluoride (KF)


Structure of Fluorine
Image courtesy of Mark Winter www.webelements.com

Electronic Configuration = [He]2s22p5

Fluorine, like the other Halogens has 7 electrons in its outer shell. It therefore has an oxidation state of -1.

Fluorine can only exist in compounds where it has an oxidation state of -1 as it is the most electronegative element.

Fluorine shows some differences to the other Halogens, as it is smaller so several Fluorine atoms can fit around a central atom.

The F-F bond is also weak as the small size of the Fluorine atom brings the lone pairs on the fluorine closer together than in the other Halogens and repulsion weakens the bond.

Occurance and Preparation

Fluorine is too reactive to occur freely in nature. It is found in Cryolite, Cacium Fluoride and Fluorspar.

It is extracted, (on an industrial scale), by the electrolysis of fused acid Potassium Fluoride in a copper vessel, using graphite electrodes at currents up to 2,000 Amperes.


Fluorine is important in the manufacture of Teflon, used for linings in pots and pans, amongst other things.

It is also used to make the freons, used in refrigerators.


As mentioned, Fluorine can only exist in compounds where it has an oxidation state of -1.

Like the other Halogens, it is a very good oxidising agent and therefore forms oxides which are thermally unstable.

It can also form oxoacids and can combine with the other Halogens to form interhalogens and polyhalide ions.

Fluorine also forms HF, a Halide. (A Halide is a colourless gas which is soluble in water.)


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Author: Gemma Higgins (document modification date: 28th March 2002)