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9. FluorineName: Fluorine
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. 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. Fluorine (Latin fluere meaning flow or flux) in the form of fluorspar (calcium fluoride) was described in 1529 by Georigius Agricola for its use as a flux, which is a substance that is used to promote the fusion of metals or minerals. In 1670 Schwandhard found that glass was etched when it was exposed to fluorspar that was treated with acid. Karl Scheele and many later researchers, including Humphry Davy, Gay-Lussac, Antoine Lavoisier, and Louis Thenard all would experiment with hydrofluoric acid, easily obtained by treating calcium fluoride (fluorspar) with concentrated sulfuric acid. It was eventually realised that hydrofluoric acid contained a previously unknown element. This element was not isolated for many years after this due to its extreme reactivity - it is separated from its compounds only with difficulty and then it immediately attacks the remaining materials of the compound. Finally in 1886 fluorine was isolated by Henri Moissan after almost 74 years of continuous effort. It was an effort which cost several researchers their health or even their lives, and for Moissan, it earned him the 1906 Nobel Prize in chemistry. The first commercial production of fluorine was needed for the atomic bomb Manhattan project in World War II where the compound uranium hexafluoride (UF6) was used to separate the U-235 and U-238 isotopes of uranium. Today both the gaseous diffusion process and the gas centrifuge process use gaseous (UF6) to produce enriched uranium for nuclear power applications. Both fluorine and HF must be handled with great care and any contact with skin and eyes should be strictly avoided. Both elemental fluorine and fluoride ions are highly toxic. When it is a free element, fluorine has a characteristic pungent odor that is detectable in concentrations as low as 20 nL/L. It is recommended that the maximum allowable concentration for a daily 8-hour time-weighted exposure is 1 μL/L (part per million by volume (lower than e.g. hydrogen cyanide) However, safe handling procedures enable the transport of liquid fluorine by the ton. Quick links
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