[158], The term perfluorinated compound is used for what would otherwise be a perfluorocarbon if not for the presence of a functional group,[159][note 17] often a carboxylic acid. The bond energy is significantly weaker than those of Cl2 or Br2 molecules and similar to the easily cleaved oxygen–oxygen bonds of peroxides or nitrogen–nitrogen bonds of hydrazines. Industrial production of fluorine gas for uranium enrichment, its largest application, began during the Manhattan Project in World War II. It is lethal at very low levels. To prevent rapid corrosion of the platinum in his electrochemical cells, he cooled the reaction to extremely low temperatures in a special bath and forged cells from a more resistant mixture of platinum and iridium, and used fluorite stoppers. In the latter case, it significantly increases the acidity of a molecule: the anion formed after giving the proton off becomes stable as a result. [41] Fluorine condenses into a bright yellow liquid at −188 °C (−306 °F), a transition temperature similar to those of oxygen and nitrogen. [22], Fluorine forms compounds with all elements except neon and helium. Global fluorochemical sales amount to more than US$15 billion a year. The chalcogens (oxygen's periodic table column) are somewhat similar: The tetrafluorides are thermally unstable and hydrolyze, and are also ready to use their lone pair to form adducts to other (acidic) fluorides. Graphite combines with fluorine above 400 °C (750 °F) to produce non-stoichiometric carbon monofluoride; higher temperatures generate gaseous fluorocarbons, sometimes with explosions. He devised a method which evolves fluorine at high yield and atmospheric pressure:[176], Christe later commented that the reactants "had been known for more than 100 years and even Moissan could have come up with this scheme. But since the transitional state is higher in energy than the hexatomic molecule, the energy difference would need to be added to reach the transitional state and thus allow the decay. [230][231][232][233] Fluorine also finds use in steroids:[234] fludrocortisone is a blood pressure-raising mineralocorticoid, and triamcinolone and dexamethasone are strong glucocorticoids. [117], The simplest fluoroplastic is polytetrafluoroethylene (PTFE, DuPont brand Teflon), which is a simple linear chain polymer with the repeating structural unit:–CF2–. Elemental Fluorine is slightly basic, which means that when it reacts with water it forms \(OH^-\). Trifluorides of plutonium, samarium (at high temperature), and lanthanum adopt the LaF3 structure. [88] The hexafluorides are the result of direct fluorination of the elements (compare: other hexahalides of these elements do not even exist). [63][193] Surfactants are a minor application but generate over $1 billion in annual revenue. [26], As a result of its small size and high negative charge density, the fluoride anion is the "hardest" base (i.e., of low polarizability). The explanation for the behavior is complicated, having to do with various cluster-forming tendencies of HF, water, and fluoride ion, as well as thermodynamic issues. [227] Fluorination also increases lipophilicity because the bond is more hydrophobic than the carbon–hydrogen bond, and this often helps in cell membrane penetration and hence bioavailability. [29] The dispersion of the charge on the anion affects the acidity of the solvated proton (in form of H2F+): The compound has an extremely low pKa of −28 and is 10 quadrillion (1016) times stronger than pure sulfuric acid. [287] An outlier is HFO-1234yf which is a new type of refrigerant called a Hydrofluoroolefin (HFO) and has attracted global demand due to its GWP of less than 1 compared to 1,430 for the current refrigerant standard HFC-134a. Zirconium, hafnium, plus many of the actinides form tetrafluorides with an ionic structure that puts the metal cation in an 8-coordinate square antiprism. [4], While an individual fluorine atom has one unpaired electron, molecular fluorine (F2) has all the electrons paired. [217][218] Reviews of the scholarly literature in 2000 and 2007 associated water fluoridation with a significant reduction of tooth decay in children. [104][105][106], Covalent bonding first comes to prominence in the tetrafluorides: those of zirconium, hafnium[107][108] and several actinides[109] are ionic with high melting points,[110][note 12] while those of titanium,[113] vanadium,[114] and niobium are polymeric,[115] melting or decomposing at no more than 350 °C (660 °F). [79][173] Regulator valves and pipework are made of nickel, the latter possibly using Monel instead. In addition, hydrogen and fluorine react to form hydrogen fluoride, which contains HF molecules. Most had no symptoms, but about 30% had stomach pains. The name later evolved into fluorspar (still commonly used) and then fluorite. [63][170] Temperatures are elevated, KF•2HF melting at 70 °C (158 °F) and being electrolyzed at 70–130 °C (158–266 °F). [218][221] The benefits of fluoridation have lessened, possibly due to other fluoride sources, but are still measurable in low-income groups. [46][47][note 3], Only one isotope of fluorine occurs naturally in abundance, the stable isotope 19F. [85][note 7], Initial studies on fluorine were so dangerous that several 19th-century experimenters were deemed "fluorine martyrs" after misfortunes with hydrofluoric acid. At room temperature, tungsten hexafluoride is a gas. Fluorine substitution, usually of a single atom or at most a trifluoromethyl group, is a robust modification with effects analogous to fluorinated pharmaceuticals: increased biological stay time, membrane crossing, and altering of molecular recognition. Hungarian-American chemist George Olah received the 1994 Nobel Prize in chemistry for investigating such reactions.[98]. About 20% of manufactured HF is a byproduct of fertilizer production, which produces hexafluorosilicic acid (H2SiF6), which can be degraded to release HF thermally and by hydrolysis: Moissan's method is used to produce industrial quantities of fluorine, via the electrolysis of a potassium fluoride/hydrogen fluoride mixture: hydrogen and fluoride ions are reduced and oxidized at a steel container cathode and a carbon block anode, under 8–12 volts, to generate hydrogen and fluorine gas respectively. [37], Dry hydrogen fluoride dissolves low-valent metal fluorides readily. [247] An Alliance Pharmaceuticals effort reached clinical trials but was abandoned because the results were not better than normal therapies.[248]. Part of. [66] The existence of gaseous fluorine in crystals, suggested by the smell of crushed antozonite, is contentious;[67][68] a 2012 study reported the presence of 0.04% F2 by weight in antozonite, attributing these inclusions to radiation from the presence of tiny amounts of uranium. And how does nitrogen react with these metals on a whole? Developed in the 1960s, it was initially deployed as fuel cell material in spacecraft and then replaced mercury-based chloralkali process cells. The rest are volatile solids. [91][195], Halogenated refrigerants, termed Freons in informal contexts,[note 18] are identified by R-numbers that denote the amount of fluorine, chlorine, carbon, and hydrogen present. [note 1] [266][271], Soluble fluorides are moderately toxic: 5–10 g sodium fluoride, or 32–64 mg fluoride ions per kilogram of body mass, represents a lethal dose for adults. The structure is tetragonal and puts metal atoms in octahedral coordination. The fluoride ion from dissolved fluoride salts inhibits dental cavities, and so finds use in toothpaste and water fluoridation. [148] Among other noble gases, krypton forms a difluoride,[149] and radon and fluorine generate a solid suspected to be radon difluoride. [240], Liquid fluorocarbons can hold large volumes of oxygen or carbon dioxide, more so than blood, and have attracted attention for their possible uses in artificial blood and in liquid breathing. PTFE has a backbone of carbons single bonded in a long chain, with all side bonds to fluorines. [84] The New Latin name fluorum gave the element its current symbol F; Fl was used in early papers. [81] Reactions with organomagnesium compounds, alcohols, amines, and ammonia yield adduction compounds. [29] Fluoroantimonic acid is so strong that it protonates otherwise inert compounds like hydrocarbons. Fluorination allows some elements to achieve relatively low[note 4] highest oxidation states that are otherwise hard to achieve. Each metric ton of aluminium requires about 23 kg (51 lb) of flux. It combines with metals, nonmetals, metalloids, and most noble gases,[96] and almost exclusively assumes an oxidation state of −1. [108][note 5] However, octafluoride anions, such as the octafluoroiodate (IF−8), octafluorozirconate (ZrF4−8), and octafluoroxenate (XeF2−8) anions are well-known. You can see the trend in reactivity if you react the halogens with iron wool. These include ciprofloxacin and levofloxacin. It will react explosively with many elements and compounds such as Hydrogen and water. This influences various peculiar aspects of hydrogen fluoride's properties. [117][139][140], Chalcogens have diverse fluorides: unstable difluorides have been reported for oxygen (the only known compound with oxygen in an oxidation state of +2), sulfur, and selenium; tetrafluorides and hexafluorides exist for sulfur, selenium, and tellurium.


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