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Electron Affinity of Fluorine is 328 kJ/mol. Electronegativity of Fluorine is 3.98. Electron Affinity. In chemistry and atomic physics, the electron affinity of an atom or molecule is defined as: the change in energy (in kJ/mole) of a neutral atom or molecule (in the gaseous phase) when an electron is added to the atom to form a negative ion. Halogen comprises fluorine, chlorine, bromine and iodine that are used in various commercial and industrial applications to improve the performance of materials. Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative element, it is extremely reactive, as it reacts with all other elements, except for argon, neon, and helium.
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Electron Affinity of Fluorine is 328 kJ/mol. Electronegativity of Fluorine is 3.98. Electron Affinity. In chemistry and atomic physics, the electron affinity of an atom or molecule is defined as: the change in energy (in kJ/mole) of a neutral atom or molecule (in the gaseous phase) when an electron is added to the atom to form a negative ion. A fluoride ion will be much less stable than a chloride or a bromide ion- it’s ionic radii is much smaller, and it’s electronegativity is the highest of all known elements. Stability relates to charge density.
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Karl ChristeSee All ContributorsFluorine Ion Atomic Number
Research Professor of Chemistry, Department of Chemistry, University of Southern California, Los Angeles, Calif.
Alternative Title: F
Fluorine (F), most reactive chemical element and the lightest member of the halogen elements, or Group 17 (Group VIIa) of the periodic table. Its chemical activity can be attributed to its extreme ability to attract electrons (it is the most electronegative element) and to the small size of its atoms.
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atomic number | 9 |
---|---|
atomic weight | 18.998403163 |
melting point | −219.62 °C (−363.32 °F) |
boiling point | −188 °C (−306 °F) |
density (1 atm, 0 °C or 32 °F) | 1.696 g/litre (0.226 ounce/gallon) |
oxidation states | −1 |
electron config. | 1s22s22p5 |
History
Fluorine Ion Protons
The fluorine-containing mineral fluorspar (or fluorite) was described in 1529 by the German physician and mineralogist Georgius Agricola. It appears likely that crude hydrofluoric acid was first prepared by an unknown English glassworker in 1720. In 1771 the Swedish chemist Carl Wilhelm Scheele obtained hydrofluoric acid in an impure state by heating fluorspar with concentrated sulfuric acid in a glass retort, which was greatly corroded by the product; as a result, vessels made of metal were used in subsequent experiments with the substance. The nearly anhydrous acid was prepared in 1809, and two years later the French physicist André-Marie Ampère suggested that it was a compound of hydrogen with an unknown element, analogous to chlorine, for which he suggested the name fluorine. Fluorspar was then recognized to be calcium fluoride.
The isolation of fluorine was for a long time one of the chief unsolved problems in inorganic chemistry, and it was not until 1886 that the French chemist Henri Moissan prepared the element by electrolyzing a solution of potassium hydrogen fluoride in hydrogen fluoride. He received the 1906 Nobel Prize for Chemistry for isolating fluorine. The difficulty in handling the element and its toxic properties contributed to the slow progress in fluorine chemistry. Indeed, up to the time of World War II the element appeared to be a laboratory curiosity. Then, however, the use of uranium hexafluoride in the separation of uranium isotopes, along with the development of organic fluorine compounds of industrial importance, made fluorine an industrial chemical of considerable use.
Occurrence and distribution
The fluorine-containing mineral fluorspar (fluorite, CaF2) has been used for centuries as a flux (cleansing agent) in various metallurgical processes. The name fluorspar is derived from the Latin fluere, “to flow.” The mineral subsequently proved to be a source of the element, which was accordingly named fluorine. The colourless, transparent crystals of fluorspar exhibit a bluish tinge when illuminated, and this property is accordingly known as fluorescence.
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Fluorine is found in nature only in the form of its chemical compounds, except for trace amounts of the free element in fluorspar that has been subjected to radiation from radium. Not a rare element, it makes up about 0.065 percent of Earth’s crust. The principal fluorine-containing minerals are (1) fluorspar, deposits of which occur in Illinois, Kentucky, Derbyshire, southern Germany, the south of France, and Russia and the chief source of fluorine, (2) cryolite (Na3AlF6), chiefly from Greenland, (3) fluoroapatite (Ca5[PO4]3[F,Cl]), widely distributed and containing variable amounts of fluorine and chlorine, (4) topaz (Al2SiO4[F,OH]2), the gemstone, and (5) lepidolite, a mica as well as a component of animal bones and teeth.
Physical and chemical properties
At room temperature fluorine is a faintly yellow gas with an irritating odour. Inhalation of the gas is dangerous. Upon cooling fluorine becomes a yellow liquid. There is only one stable isotope of the element, fluorine-19.
Because fluorine is the most electronegative of the elements, atomic groupings rich in fluorine are often negatively charged. Methyl iodide (CH3I) and trifluoroiodomethane (CF3I) have different charge distributions as shown in the following formulas, in which the Greek symbol δ indicates a partial charge:
The first ionization energy of fluorine is very high (402 kilocalories per mole), giving a standard heat formation for the F+ cation of 420 kilocalories per mole.
The small size of the fluorine atom makes it possible to pack a relatively large number of fluorine atoms or ions around a given coordination centre (central atom) where it forms many stable complexes—for example, hexafluorosilicate (SiF6)2− and hexafluoroaluminate (AlF6)3−. Fluorine is the most powerfully oxidizing element. No other substance, therefore, is able to oxidize the fluoride anion to the free element, and for this reason the element is not found in the free state in nature. For more than 150 years, all chemical methods had failed to produce the element, success having been achieved only by the use of electrolytic methods. However, in 1986 American chemist Karl O. Christe reported the first chemical preparation of fluorine, where “chemical preparation” means a method that does not use techniques such as electrolysis, photolysis, and discharge or use fluorine itself in the synthesis of any of the starting materials. He used K2MnF6 and antimony pentafluoride (SbF5), both of which can be easily prepared from HF solutions.
The high oxidizing power of fluorine allows the element to produce the highest oxidation numbers possible in other elements, and many high oxidation state fluorides of elements are known for which there are no other corresponding halides—e.g., silver difluoride (AgF2), cobalt trifluoride (CoF3), rhenium heptafluoride (ReF7), bromine pentafluoride (BrF5), and iodine heptafluoride (IF7).
Fluorine Ions
Fluorine (F2), composed of two fluorine atoms, combines with all other elements except helium and neon to form ionic or covalent fluorides. Some metals, such as nickel, are quickly covered by a fluoride layer, which prevents further attack of the metal by the element. Certain dry metals, such as mild steel, copper, aluminum, or Monel (a 66 percent nickel, 31.5 percent copper alloy), are not attacked by fluorine at ordinary temperatures. For work with fluorine at temperatures up to 600 °C (1,100 °F), Monel is suitable; sintered alumina is resistant up to 700 °C (1,300 °F). When lubricants are required, fluorocarbon oils are most suitable. Fluorine reacts violently with organic matter (such as rubber, wood, and cloth), and controlled fluorination of organic compounds by the action of elemental fluorine is only possible if special precautions are taken.
Quick Facts
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Chemical properties of fluorine - Health effects of fluorine - Environmental effects of fluorine
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Fluorine Ion Electron Configuration
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Small amounts of fluorine are naturally present in water, air, plants and animals. As a result humans are exposed to fluorine through food and drinking water and by breathing air. Fluorine can be found in any kind of food in relatively small quantities. Large quantities of fluorine can be found in tea and shellfish. Fluorine is essential for the maintenance of solidity of our bones. Fluorine can also protect us from dental decay, if it is applied through toothpaste twice a day. If fluorine is absorbed too frequently, it can cause teeth decay, osteoporosis and harm to kidneys, bones, nerves and muscles. Fluorine gas is released in the industries. This gas is very dangerous, as it can cause death at very high concentrations. At low concentrations it causes eye and nose irritations. |
Environmental effects of fluorine
When fluorine from the air ends up in water it will settle into the sediment. When it ends up in soils, fluorine will become strongly attached to soil particles. In the environment fluorine cannot be destroyed; it can only change form. Fluorine that is located in soils may accumulate in plants. The amount of uptake by plants depends upon the type of plant and the type of soil and the amount and type of fluorine found in the soil. With plants that are sensitive for fluorine exposure even low concentrations of fluorine can cause leave damage and a decline in growth. Too much fluoride, wheater taken in form the soil by roots, or asdorbed from the atmosphere by the leaves, retards the growth of plants and reduces crop yields. Those more affected are corns and apricots. Animals that eat fluorine-containing plants may accumulate large amounts of fluorine in their bodies. Fluorine primarily accumulates in bones. Consequently, animals that are exposed to high concentrations of fluorine suffer from dental decay and bone degradation. Too much fluorine can also cause the uptake of food from the paunch to decline and it can disturb the development of claws. Finally, it can cause low birth-weights. |
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