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Lithium () is a Chemical Element with the symbol '''Li''' and Atomic Number 3. It is a soft Alkali Metal with a silver-white color. Under Standard Conditions , it is the lightest Metal and the least dense Solid element. Like all alkali metals, lithium is highly reactive, Corroding quickly in moist Air to form a black tarnish. For this reason, lithium metal is typically stored under the cover of Oil . Lithium (mostly 7Li) was one of the few elements synthesized in the Big Bang , although its quantity has vastly decreased. The reasons for its disappearance and the processes by which new lithium is created continue to be important matters of study in Astronomy . Lithium is the 33rd most abundant element on Earth ,1 but due to its high Reactivity only appears there naturally in the form of Compounds . Lithium occurs in a number of Pegmatitic Mineral s, but is also commonly obtained from Brine s and Clay s; on a commercial scale, lithium metal is isolated Electrolytically from a mixture of Lithium Chloride and Potassium Chloride . Trace amounts of lithium are present in the of lithium atoms was the first man-made Nuclear Reaction , and Lithium Deuteride serves as the Fusion fuel in Staged Thermonuclear Weapon s. CHARACTERISTICS Like other Alkali Metal s, lithium has a single Valence Electron which it will readily lose to form a Cation , indicated by the element's low Electronegativity . As a result, lithium is easily deformed, highly reactive, and has lower Melting and Boiling Point s than most metals. However, these and many other properties attributable to alkali metals' weakly-held valence electron are most diminished in lithium, as it possesses the smallest Atomic Radius and thus the highest electronegativity. In addition, lithium has a Diagonal Relationship with Magnesium , an element of similar atomic and Ionic Radius . Chemical resemblances between the two metals include the formation of a Nitride in N2, the formation of an Oxide when burnt in O2, Salts with similar Solubilities , and thermally-instable Carbonate s and nitrides.Kamienski et al. "Lithium and lithium compounds". ''Kirk-Othmer Encyclopedia of Chemical Technology''. John Wiley & Sons, Inc. Published online 2004. Physical Lithium is soft enough to be cut with a knife, though this is more difficult than cutting sodium. The fresh metal has a silvery-white color which only remains untarnished in dry air. Lithium has about half the density of water, giving solid sticks of lithium metal the odd heft of a light-to-medium wood like Pine . The metal floats highly in Hydrocarbon s; in the laboratory, jars of lithium are typically composed of black-coated sticks held down in hydrocarbon mechanically by the jar's lid and other sticks. Lithium is greatly heat-resistant, possessing a low Coefficient Of Thermal Expansion and the highest Specific Heat Capacity of any solid element. Lithium has also been found to be Superconductive below 400 μK . This finding paves the way for further study of superconductivity, as lithium's Atomic Lattice is the simplest of all metals. Chemical In moist air, lithium metal rapidly tarnishes to form a black coating of Lithium Hydroxide (LiOH and LiOH·H2O), Lithium Nitride (Li3N) and Lithium Carbonate (Li2CO3, the result of a secondary reaction between LiOH and CO2 ). When placed over a flame, lithium gives off a striking Crimson color, but when it burns strongly, the flame becomes a brilliant white. Lithium will ignite and burn when exposed to water and water vapours in oxygen. It is the only metal that reacts with nitrogen at room temperature. Lithium metal is flammable and potentially explosive when exposed to air and especially water, though it is far less dangerous than other alkali metals in this regard. The lithium-water reaction at normal temperatures is brisk but not violent. Lithium fires are difficult to extinguish, requiring special chemicals designed to smother them. HISTORY Petalite was first described in 1800 by the Brazilian scientist José Bonifácio De Andrade E Silva , who discovered the mineral in a Swedish Iron Mine on the island of Utö . However, it was not until 1817 that Johan August Arfwedson , then a trainee in the laboratory of Jöns Jakob Berzelius , Discovered the presence of a new element while analyzing petalite ore. The element formed compounds similar to those of Sodium and Potassium , though its Carbonate and Hydroxide were less Water Soluble . It was given the name "lithion", from the Greek ''λιθoς'' (''lithos'', "stone"), to reflect its discovery in a mineral, as opposed to sodium and potassium which had been discovered in Plant tissue; its name would later be standardized as "lithium". Arfwedson later showed that this same element was present in the mineral ores Spodumene and Lepidolite . In 1818 , Christian Gmelin was the first to observe that lithium salts give a bright red color in flame. However, both Arfwedson and Gmelin tried and failed to isolate the element from its salts.23 The element was not isolated until 1818, when William Thomas Brande performed Electrolysis on Lithium Oxide , a process which had previously been employed by Sir Humphry Davy to isolate potassium and sodium. In 1855, Robert Bunsen and Augustus Matthiessen produced large quantities of the metal by electrolysis of Lithium Chloride . Commercial production of lithium metal began in 1923 by the German company Metallgesellschaft through the electrolysis of a molten mixture of lithium chloride and Potassium Chloride . OCCURRENCE AND PRODUCTION Natural abundance ''See also .'' Lithium is widely distributed on Earth and is the 33rd most abundant element; however, it does not naturally occur in elemental form due to its high reactivity. Estimates for Crustal content range from 20 to 70 ppm by weight. In keeping with its name, lithium forms a minor part of Igneous rocks, with the largest concentrations in Granite s. Granitic Pegmatite s also provide the greatest abundance of lithium-containing minerals, with Spodumene and Petalite being the most commercially-viable mineral sources for the element. In humans, lithium compounds have not been found to play a natural biological role; large amounts are slightly toxic. Lithium appears to be an essential trace element for goats, and possibly rats, suggesting a role in humans by analogy. However, the essentiality of ultratrace mineral in humans is far more difficult to determine, due to the difficulty and ethical issues involved with the experiments, which involve total isolation from the environment, and unpalatable semi-synthetic foods. Modern extraction Since the end of World War II , lithium metal production has greatly increased. The metal is separated from other elements in igneous mineral such as those above, and is also extracted from the water of Mineral Springs . The metal is produced Electrolytically from a mixture of fused lithium and Potassium Chloride . In 1998 it was about US$ 43 per Pound ($95 per Kg ).4 Chile is currently the leading lithium metal producer in the world, with Argentina next. Both countries recover the lithium from brine pools. In the United States lithium is similarly recovered from brine pools in Nevada .5 China may emerge as a significant producer of brine-based lithium carbonate towards the end of this decade. Potential capacity of up to 45,000 tonnes per year could come on-stream if projects in Qinghai province and Tibet proceed. ISOTOPES See Also: Isotopes of lithium Naturally occurring lithium is composed of two stable Isotope s 6Li and 7Li, the latter being the more abundant (92.5% Natural Abundance ). Seven Radioisotope s have been characterized, the most stable being 8Li with a Half-life of 838 Ms and 9Li with a half-life of 178.3 ms. All of the remaining Radioactive isotopes have half-lives that are shorter than 8.6 ms. The shortest-lived isotope of lithium is 4Li which decays through Proton Emission and has a half-life of 7.58043x10-23 s. 7Li is one of the Primordial Elements or, more properly, primordial isotopes, produced in Big Bang Nucleosynthesis (a small amount of 6Li is also produced in stars). Lithium isotopes fractionate substantially during a wide variety of natural processes, including Mineral Formation (chemical precipitation), Metabolism , and Ion Exchange . Lithium ion substitutes for Magnesium and Iron in octahedral sites in Clay minerals, where 6Li is preferred to 7Li, resulting in enrichment of the light isotope in processes of hyperfiltration and rock alteration. The exotic 11Li is known to exhibit a Nuclear Halo . APPLICATIONS Because of its Specific Heat capacity, the highest of all Solid s, lithium is often used in heat transfer applications. It is an important ingredient in Cathode materials, used in rechargeable and single-use Batteries because of its high Electrochemical Potential , light weight, and high current density. Large quantities of lithium are also used in the manufacture of Organolithium Reagent s, especially N-butyllithium which has many uses in fine chemical and Polymer synthesis. Medical Use See Also: Lithium pharmacology Lithium salts such as Lithium Carbonate (Li2CO3), Lithium Citrate , and Lithium Orotate are mood stabilizers. They are used in the treatment of Bipolar Disorder , since unlike most other mood altering drugs, they counteract both Mania and Depression . Lithium can also be used to augment other Antidepressant drugs. It is also sometimes prescribed as a preventive treatment for Migraine disease and Cluster Headache s. The active principle in these salts is the lithium ion Li+, which interacts with the normal function of sodium ions to produce numerous changes in the neurotransmitter activity of the brain. Therapeutically useful amounts of lithium are only slightly lower than toxic amounts, so the blood levels of lithium must be carefully monitored during treatment. Common side effects include muscle tremors, twitching, Ataxia , Nephrogenic Diabetes Insipidus (polyuria and polydipsia) and seizures. Most of the side-effects are a result caused by the increased elimination of potassium. Other uses
REGULATION Some jurisdictions limit the sale of Lithium Batteries , which are the most readily available source of lithium metal for ordinary consumers. Lithium can be used to reduce pseudoephedrine and ephedrine to Methamphetamine in the Birch Reduction method, which employs solutions of alkali metals dissolved in anhydrous ammonia. However, the effectiveness of such restrictions in controlling illegal production of methamphetamine remains indeterminate and controversial. Carriage and shipment of some kinds of lithium batteries may be prohibited aboard certain types of transportation (particularly aircraft), because of the ability of most types of lithium batteries to fully discharge very rapidly when Short-circuited , leading to overheating and possible Explosion . However, most consumer lithium batteries have thermal overload protection built-in to prevent this type of incident, or their design inherently limits short-circuit currents. Lithium is a component for Thermonuclear Weapons (so called "hydrogen bombs") and applications of lithium for this purpose in the Nuclear Weapons industry is pursued in developing nuclear powers like India, and presumably others. PRECAUTIONS Lithium metal, due to its alkaline tarnish, is corrosive and requires special handling to avoid skin contact. Breathing lithium dust or lithium compounds (which are often alkaline) can irritate the nose and throat; higher exposure to lithium can cause a build-up of fluid in the lungs, leading to Pulmonary Edema . The metal itself is usually less a handling hazard than the caustic hydroxide produced when it is in contact with moisture. Lithium should be stored in a non-reactive compound such as Naphtha or a hydrocarbon. SEE ALSO REFERENCES EXTERNAL LINKS
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