Fluorine (atomic symbol F) is a pale yellow, corrosive, and flammable halogen gas. It is atomic number 9, located in period 2 and group 17 of the periodic table. The halogens are salt-forming non-metals, and fluorine is the lightest of these. Fluorine is the most electronegative and reactive of all elements, reacting extremely vigorously with all other elements except oxygen, helium, neon and krypton. The name fluorine was derived from fluorospar (CaF2), a mineral used in metal refining. Fluorospar is composed mainly of calcium fluoride and it combines with the unwanted minerals found in metal ores allowing the desired ores to flow and be collected. Fluorospar was named from the Latin word “fluere,” meaning “to flow.”
The German mineralogist Georgius Agricola, described fluorospar in 1530, but the element fluorine had not yet been identified. In the late 1600s, there are documented uses of other fluorine compounds being used to etch glass, and George Gore finally produced a small amount of fluorine via electrolysis in 1869. Unfortunately his experiment exploded because the fluorine combined with the hydrogen gas that formed on the other electrode. A number of other chemists performed experiments with fluorine in the 1800s like Gay Lussac and Humphrey Davy. Most of the experiments produced deadly hydrofluoric acid (HF), and a lot of accidents occurred. The first successful isolation of fluorine occurred in 1866 when the French chemist Ferdinand Frederick Henri Moissan used electrolysis with potassium fluoride (KF) and hydrofluoric acid. He managed to separate the fluorine from the hydrogen with his device made of platinum, and he ultimately won a Nobel Prize for his work in 1906. Today, his methods are still one of the ways we obtain fluorine for commercial use.
Prior to World War II there was essentially no use for fluorine. The element gained recognition in atomic bomb projects because of its dangerous properties as well as refining abilities. Uranium hexafluoride is used in the processing nuclear fuel to generate uranium. Elemental fluorine demands very careful storage, handling and transport, but despite how treacherous it may seem to interact with, fluorine it has surprising everyday uses, particularly in its salt forms. Today fluoride, the anion of fluorine, is added to city water supplies to prevent tooth decay. It is also found in many compounds used in toothpaste, mainly sodium fluoride, for the same reason. Sodium fluoride is a harmless, water-soluble salt. Fluorospar is now used to make lenses that focus infrared light. Fluorocarbons, compounds containing both fluorine and carbon, are known to be detrimental to the ozone layer, but were widely used in air conditioning, refrigeration and other cooling systems.