Fluoride

Fluoride (/ˈflʊəraɪd, ˈflɔːr-/) is an inorganic, monatomic anion with the chemical formula F− (also written −), whose salts are typically white or colorless. Fluoride salts typically have distinctive bitter tastes, and are odorless. Its salts and minerals are important chemical reagents and industrial chemicals, mainly used in the production of hydrogen fluoride for fluorocarbons. Fluoride is classified as a weak base since it only partially associates in solution, but concentrated fluoride is corrosive and can attack the skin.F− +  H+ → HF    (1)F− + H2O ↽ − ⇀ {displaystyle {ce {<<=>}}} HF + HO−    (2) Fluoride (/ˈflʊəraɪd, ˈflɔːr-/) is an inorganic, monatomic anion with the chemical formula F− (also written −), whose salts are typically white or colorless. Fluoride salts typically have distinctive bitter tastes, and are odorless. Its salts and minerals are important chemical reagents and industrial chemicals, mainly used in the production of hydrogen fluoride for fluorocarbons. Fluoride is classified as a weak base since it only partially associates in solution, but concentrated fluoride is corrosive and can attack the skin. Fluoride is the simplest fluorine anion. In terms of charge and size, the fluoride ion resembles the hydroxide ion. Fluoride ions occur on earth in several minerals, particularly fluorite, but are present only in trace quantities in bodies of water in nature. Fluorides include compounds that contain both ionic fluoride and those where fluoride does not dissociate. The nomenclature does not distinguish these situations. For example, sulfur hexafluoride and carbon tetrafluoride are not sources of fluoride ions under ordinary conditions. The systematic name fluoride, the valid IUPAC name, is determined according to the additive nomenclature. However, the name fluoride is also used in compositional IUPAC nomenclature which does not take the nature of bonding involved into account.Fluoride is also used non-systematically, to describe compounds which release fluoride upon dissolving. Hydrogen fluoride is itself an example of a non-systematic name of this nature. However, it is also a trivial name, and the preferred IUPAC name for fluorane. Fluorine is estimated to be the 13th-most abundant element in the earth's crust and is widely dispersed in nature, almost entirely in the form of fluorides. Many minerals are known, but of paramount commercial importance is fluorite (CaF2), which is roughly 49% fluoride by mass. The soft, colorful mineral is found worldwide. Fluoride is naturally present at low concentration in most fresh and saltwater sources and may also be present in rain water. Seawater fluoride levels are usually in the range of 0.86 to 1.4 mg/L, and average 1.1 mg/L (milligrams per litre). For comparison, chloride concentration in seawater is about 19 g/L. The low concentration of fluoride reflects the insolubility of the alkaline earth fluorides, e.g., CaF2. Concentrations in fresh water vary more significantly. Surface water such as rivers or lakes generally contains between 0.01–0.3 ppm. Groundwater (well water) concentrations vary even more, depending on the presence of local fluoride-containing minerals. For example, natural levels of under 0.05 mg/L have been detected in parts of Canada but up to 8 mg/L in parts of China; in general levels rarely exceed 10 mg/litre Fluoride can be present in rain, with its concentration increasing significantly upon exposure to volcanic activity or atmospheric pollution derived from burning fossil fuels or other sorts of industry. All vegetation contains some fluoride, which is absorbed from soil and water. Some plants concentrate fluoride from their environment more than others. All tea leaves contain fluoride; however, mature leaves contain as much as 10 to 20 times the fluoride levels of young leaves from the same plant.