Fluorine: the essentials
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. It is not uncommon to see fluorine spelled incorrectly as flourine.
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.
Cartoon by Nick D Kim ([Science and Ink], used by permission).
Fluorine: historical information
In 1670 a recipe containing Bohemian emerald (now known as calcium fluoride, CaF2) was used to etch glass. It seems that George Gore made a little fluorine through an electrolytic process but his apparatus exploded when the fluorine produced reacted with hydrogen from the other electrode. The element finally was isolated in 1886 by Ferdinand Frederic Henri Moisson who used an apparatus constructed from platinum. His reward was the Nobel Prize for chemistry in 1906.
Fluorine around us Read more »
Fluorine as fluoride (F-) is probably an essential element for humans and certainly is for some molluscs. In some areas, fluoride ion is added to drinking water (in very low concentrations) since it renders tooth enamel relatively immune to bacteriological attack. It does this by replacing the OH group of hydroxyapatite with fluoride. In other areas, fluoride is not added to water, despite the benefits, as a consequence of protests from civil rights activists who object to the addition of anything to water.
Fluorine gas is never found as the free gas in nature and is always found as the fluoride. Fluorine occurs chiefly in fluorspar (or fluorite, calcium difluoride, CaF2), cryolite (Na2AlF6), and in many other minerals.
|Location||ppb by weight||ppb by atoms||Links|
|Human||37000 ppb by weight||12000 atoms relative to C = 1000000|
Physical properties Read more »
Heat properties Read more »
- Melting point: 53.53 [‑219.62 °C (‑363.32 °F)] K
- Boiling point: 85.03 [‑188.12 °C (‑306.62 °F)] K
- Enthalpy of fusion: 0.26 (per mol F atoms) kJ mol-1
Crystal structure Read more »
The solid state structure of fluorine is: monoclinic.
Fluorine: orbital properties Read more »
Fluorine atoms have 9 electrons and the shell structure is 2.7. The ground state electronic configuration of neutral Fluorine is [He].2s2.2p5 and the term symbol of Fluorine is 2P3/2.
- Pauling electronegativity: 3.98 (Pauling units)
- First ionisation energy: 1681.0 kJ mol‑1
- Second ionisation energy: 3374.2 kJ mol‑1
Isolation: it would never be necessary to make fluorine gas in most laboratories. Fluorine is available commercially in cylinders but is very difficult to handle. Fluorine may be recovered with difficulty as a highly reactive and corrosive pale yellow gas by electrolysis of hot molten mixtures (1:2) of potassium fluoride (KF) and hydrogen fluoride (HF). The electrolyte is corrosive, so is the product. Grease must be avoided because of the fire hazard. It is difficult to store as it reacts with most materials but steel and Monel metal containers may be used as the metal surfaces deactivate through the formation of unreactive surface fluorides.
Fluorine isotopes Read more »