Tungsten, also known as wolfram, is a chemical element with the chemical symbol W and atomic number 74. The word tungsten comes from the Swedish language tung sten directly translatable to heavy stone,[3] though the name is volfram in Swedish to distinguish it from Scheelite, which in Swedish is alternatively named tungsten. A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as a metal in 1783. Its important ores include wolframite and scheelite. The free element is remarkable for its robustness, especially the fact that it has the highest melting point of all the elements. Also remarkable is its high density of 19.3 times that of water, comparable to that of uranium and gold, and much higher (about 1.7 times) than that of lead.[4] Tungsten with minor amounts of impurities is often brittle[5] and hard, making it difficult to work. However, very pure tungsten, though still hard, is more ductile, and can be cut with a hard-steel hacksaw.[6] Tungsten's many alloys have numerous applications, most notably in incandescent light bulb filaments, X-ray tubes (as both the filament and target), electrodes in TIG welding, and superalloys. Tungsten's hardness and high density give it military applications in penetrating projectiles. Tungsten compounds are most often used industrially as catalysts. Tungsten is the only metal from the third transition series that is known to occur in biomolecules, where it is used in a few species of bacteria and archaea. It is the heaviest element known to be used by any living organism. Tungsten interferes with molybdenum and copper metabolism, and is somewhat toxic to animal life.[7][8] Contents [hide] 1 Characteristics 1.1 Physical properties 1.2 Isotopes 1.3 Chemical properties 1.4 Occurrence 1.5 Biological role 2 History 2.1 Etymology 3 Production 4 Applications 4.1 Hard materials 4.2 Alloys 4.3 Armaments 4.4 Chemical applications 4.5 Niche uses 4.6 Gold substitution 4.7 Electronics 5 Precautions 6 Patent claim 7 See also 8 References 9 External links Characteristics[edit] Physical properties[edit] In tungsten's raw form, it is a hard steel-grey metal that is often brittle and hard to work. If made very pure, tungsten retains its hardness (which exceeds that of many steels), and becomes malleable enough that it can be worked easily.[6] It is worked by forging, drawing, or extruding. Tungsten objects are also commonly formed by sintering. Of all metals in pure form, tungsten has the highest melting point (3,422 °C, 6,192 °F), lowest vapor pressure (at temperatures above 1,650 °C, 3,000 °F) and the highest tensile strength.[9] Tungsten has the lowest coefficient of thermal expansion of any pure metal. The low thermal expansion and high melting point and tensile strength of tungsten originate from strong covalent bonds formed between tungsten atoms by the 5d electrons.[10] Alloying small quantities of tungsten with steel greatly increases its toughness.[4] Tungsten exists in two major crystalline forms: α and β. The former has a body-centered cubic structure and is the most stable form. The structure of the β phase is called A15 cubic; it is metastable, but can coexist with the α phase at ambient conditions owing to non-equilibrium synthesis or stabilization by impurities. Contrary to the α phase which crystallizes in isometric grains, the β form exhibits a columnar habit. The α phase has a three times lower electrical resistivity[11] and a much lower superconducting transition temperature TC than the β phase: ca. 0.015 K vs. 1–4 K; mixing the two phases allows obtaining intermedicate TC values.[12][13] The TC value can also be raised by alloying tungsten with another metal (e.g. 7.9 K for W-Tc).[14] Such tungsten alloys are sometimes used in low-temperature superconducting circuits.[15][16][17] Isotopes[edit] Main article: Isotopes of tungsten Naturally occurring tungsten consists of five isotopes whose half-lives are so long that they can be considered stable. Theoretically, all five can decay into isotopes of element 72 (hafnium) by alpha emission, but only 180W has been observed[18] to do so with a half-life of (1.8 ± 0.2)×1018 years; on average, this yields about two alpha decays of 180W in one gram of natural tungsten per year.[19] The other naturally occurring isotopes have not been observed to decay, constraining their half-lives to be 182W, T1/2 > 1.7×1020 years 183W, T1/2 > 8×1019 years 184W, T1/2 > 1.8×1020 years 186W, T1/2 > 4.1×1018 years Another 30 artificial radioisotopes of tungsten have been characterized, the most stable of which are 181W with a half-life of 121.2 days, 185W with a half-life of 75.1 days, 188W with a half-life of 69.4 days, 178W with a half-life of 21.6 days, and 187W with a half-life of 23.72 h.[19] All of the remaining radioactive isotopes have half-lives of less than 3 hours, and most of these have half-lives below 8 minutes.[19] Tungsten also has 4 meta states, the most stable being 179mW (T½ 6.4 minutes). Chemical properties[edit] Main article: Tungsten compounds Elemental tungsten resists attack by oxygen, acids, and alkalis.[20] The most common formal oxidation state of tungsten is +6, but it exhibits all oxidation states from −2 to +6.[20][21] Tungsten typically combines with oxygen to form the yellow tungstic oxide, WO3, which dissolves in aqueous alkaline solutions to form tungstate ions, WO2− 4. Tungsten carbides (W2C and WC) are produced by heating powdered tungsten with carbon. W2C is resistant to chemical attack, although it reacts strongly with chlorine to form tungsten hexachloride (WCl6).[4] In aqueous solution, tungstate gives the heteropoly acids and polyoxometalate anions under neutral and acidic conditions. As tungstate is progressively treated with acid, it first yields the soluble, metastable "paratungstate A" anion, W 7O6– 24, which over time converts to the less soluble "paratungstate B" anion, H 2W 12O10– 42.[22] Further acidification produces the very soluble metatungstate anion, H 2W 12O6– 40, after which equilibrium is reached. The metatungstate ion exists as a symmetric cluster of twelve tungsten-oxygen octahedra known as the Keggin anion. Many other polyoxometalate anions exist as metastable species. The inclusion of a different atom such as phosphorus in place of the two central hydrogens in metatungstate produces a wide variety of heteropoly acids, such as phosphotungstic acid H3PW12O40. Tungsten trioxide can form intercalation compounds with alkali metals. These are known as bronzes; an example is sodium tungsten bronze. Occurrence[edit] Tungsten is found in the minerals wolframite (iron-manganese tungstate, (Fe,Mn)WO4), scheelite (calcium tungstate, (CaWO4), ferberite (FeWO4) and hübnerite (MnWO4). China produced 51,000 tonnes of tungsten concentrate in 2009, which was 83% of the world output. In the prelude to WWII China's production of tungsten played a role as China could use this leverage to demand material assistance from the US government.[23] Most of the remaining production originated from Russia (2,500 t), Canada (1,964 t), Bolivia (1,023 t), Austria (900 t), Portugal (900 t), Thailand (600 t), Brazil (500 t), Peru (500 t) and Rwanda (500 t).[24] Tungsten is also considered to be a conflict mineral due to the unethical mining practices observed in the Democratic Republic of the Congo.[25][26] Biological role[edit] Tungsten, at atomic number 74, is the heaviest element known to be biologically functional, with the next heaviest being iodine (Z = 53). It is used by some bacteria, but not in eukaryotes. For example, enzymes called oxidoreductases use tungsten similarly to molybdenum by using it in a tungsten-pterin complex with molybdopterin (molybdopterin, despite its name, does not contain molybdenum, but may complex with either molybdenum or tungsten in use by living organisms). Tungsten-using enzymes typically reduce carboxylic acids to aldehydes.[27] The tungsten oxidoreductases may also catalyse oxidations. The first tungsten-requiring enzyme to be discovered also requires selenium, and in this case the tungsten-selenium pair may function analogously to the molybdenum-sulfur pairing of some molybdenum cofactor-requiring enzymes.[28] One of the enzymes in the oxidoreductase family which sometimes employ tungsten (bacterial formate dehydrogenase H) is known to use a selenium-molybdenum version of molybdopterin.[29] Although a tungsten-containing xanthine dehydrogenase from bacteria has been found to contain tungsten-molydopterin and also non-protein bound selenium, a tungsten-selenium molybdopterin complex has not been definitively described.[30] In soil, tungsten metal oxidizes to the tungstate anion. It can be selectively or non-selectively imported by some prokaryotic organisms and may substitute for molybdate in certain enzymes. Its effect on the action of these enzymes is in some cases inhibitory and in others positive.[31] The soil's chemistry determines how the tungsten polymerizes; alkaline soils cause monomeric tungstates; acidic soils cause polymeric tungstates.[32] Sodium tungstate and lead have been studied for their effect on earthworms. Lead was found to be lethal at low levels and sodium tungstate was much less toxic, but the tungstate completely inhibited their reproductive ability.[33] Tungsten has been studied as a biological copper metabolic antagonist, in a role similar to the action of molybdenum. It has been found that tetrathiotungstates may be used as biological copper chelation chemicals, similar to the tetrathiomolybdates.[34]

John Cena muting everyone? Oh the irony.

You sound like a loser.

Ytterbium is a chemical element with symbol Yb and atomic number 70. It is the fourteenth and penultimate element in the lanthanide series, or last element in the f-block, which is the basis of the relative stability of the +2 oxidation state. However, like the other lanthanides, the most common oxidation state is +3, seen in its oxide, halides and other compounds. In aqueous solution, like compounds of other late lanthanides, soluble ytterbium compounds form complexes with nine water molecules. Because of its closed-shell electron configuration, its density and melting and boiling points differ from those of the other lanthanides. In 1878, the Swiss chemist Jean Charles Galissard de Marignac separated in the rare earth "erbia" another independent component, which he called "ytterbia", for Ytterby, the village in Sweden near where he found the new component of erbium. He suspected that ytterbia was a compound of a new element that he called "ytterbium" (in total, four elements were named after the village, the others being yttrium, terbium and erbium). In 1907, the new earth "lutecia" was separated from ytterbia, from which the element "lutecium" (now lutetium) was extracted by Georges Urbain, Carl Auer von Welsbach, and Charles James. After some discussion, Marignac's name "ytterbium" was retained. A relatively pure sample of the metal was obtained only in 1953. At present, ytterbium is mainly used as a dopant of stainless steel or active laser media, and less often as a gamma ray source. Natural ytterbium is a mixture of seven stable isotopes, which altogether are present at concentrations of 3 parts per million. This element is mined in China, the United States, Brazil, and India in form of the minerals monazite, euxenite, and xenotime. The ytterbium concentration is low, because the element is found among many other rare earth elements; moreover, it is among the least abundant ones. Once extracted and prepared, ytterbium is somewhat hazardous as an eye and skin irritant. The metal is a fire and explosion hazard. Contents [hide] 1 Characteristics 1.1 Physical properties 1.2 Chemical properties 1.3 Yb(II) vs. Yb(III) 1.4 Isotopes 2 Occurrence 3 Production 4 Compounds 4.1 Halides 4.2 Oxides 5 History 6 Applications 6.1 Source of gamma rays 6.2 World's most stable atomic clock 6.3 Doping of stainless steel 6.4 Ytterbium as dopant of active media 6.5 Others 7 Precautions 8 References 9 Further reading 10 External links Characteristics[edit] Physical properties[edit] Ytterbium is a soft, malleable and ductile chemical element that displays a bright silvery luster when in its pure form. It is a rare earth element, and it is readily attacked and dissolved by the strong mineral acids. It reacts slowly with cold water and it oxidizes slowly in air.[1] Ytterbium has three allotropes labeled by the Greek letters alpha, beta and gamma; their transformation temperatures are −13 °C and 795 °C,[1] although the exact transformation temperature depends on the pressure and stress.[2] The beta allotrope exists at room temperature, and it has a face-centered cubic crystal structure. The high-temperature gamma allotrope has a body-centered cubic crystalline structure.[1] The alpha allotrope has a hexagonal crystalline structure and is stable at low temperatures.[3] Normally, the beta allotrope has a metallic electrical conductivity, but it becomes a semiconductor when exposed to a pressure of about 16,000 atmospheres (1.6 GPa). Its electrical resistivity increases ten times upon compression to 39,000 atmospheres (3.9 GPa), but then drops to about 10% of its room-temperature resistivity at about 40,000 atm (4.0 GPa).[1][4] In contrast with the other rare-earth metals, which usually have antiferromagnetic and/or ferromagnetic properties at low temperatures, ytterbium is paramagnetic at temperatures above 1.0 kelvin.[5] However, the alpha allotrope is diamagnetic.[2] With a melting point of 824 °C and a boiling point of 1196 °C, ytterbium has the smallest liquid range of all the metals.[1] Contrary to most other lanthanides, which have a close-packed hexagonal lattice, ytterbium crystallizes in the face-centered cubic structure. As a result, its density (6.973 g/cm3) is significantly lower than, e.g., those of the neighboring elements thulium (9.32 g/cm3) and lutetium (9.841 g/cm3). The melting and boiling points of ytterbium are also significantly lower than those of thulium and lutetium. These properties stem from the closed-shell electron configuration of ytterbium ([Xe] 4f14 6s2), which causes only the two 6s electrons to be available for metallic bonding (in contrast to the other lanthanides where three electrons are available).[3] Chemical properties[edit] Ytterbium metal tarnishes slowly in air. Finely dispersed ytterbium readily oxidizes in air and under oxygen. Mixtures of powdered ytterbium with polytetrafluoroethylene or hexachloroethane burn with a luminous emerald-green flame.[6] Ytterbium reacts with hydrogen to form various non-stoichiometric hydrides. Ytterbium dissolves slowly in water, but quickly in acids, liberating hydrogen gas.[3] Ytterbium is quite electropositive, and it reacts slowly with cold water and quite quickly with hot water to form ytterbium(III) hydroxide:[7] 2 Yb (s) + 6 H2O (l) → 2 Yb(OH)3 (aq) + 3 H2 (g) Ytterbium reacts with all the halogens:[7] 2 Yb (s) + 3 F2 (g) → 2 YbF3 (s) [white] 2 Yb (s) + 3 Cl2 (g) → 2 YbCl3 (s) [white] 2 Yb (s) + 3 Br2 (g) → 2 YbBr3 (s) [white] 2 Yb (s) + 3 I2 (g) → 2 YbI3 (s) [white] The ytterbium(III) ion absorbs light in the near infrared range of wavelengths, but not in visible light, so the mineral ytterbia, Yb2O3, is white in color and the salts of ytterbium are also colorless. Ytterbium dissolves readily in dilute sulfuric acid to form solutions that contain the colorless Yb(III) ions, which exist as nonahydrate complexes:[7] 2 Yb (s) + 3 H2SO4 (aq) → 2 [Yb(H2O)9]3+ (aq) + 3 SO2− 4 (aq) + 3 H2 (g) Yb(II) vs. Yb(III)[edit] Although usually trivalent, ytterbium readily forms divalent compounds. This behavior is unusual to most lanthanides, which almost exclusively form compounds with an oxidation state of +3. The +2 state has an valence electron configuration of 4f14 because the fully filled f-shell gives more stability. The yellow-green ytterbium(II) ion is a very strong reducing agent and decomposes water, releasing hydrogen gas, and thus only the colorless ytterbium(III) ion occurs in aqueous solution. Samarium and thulium also behave this way in the +2 state, but europium(II) is stable in aqueous solution. Ytterbium(II) behaves similarly to europium(II) and the alkaline earth metals, dissolving in ammonia to form blue electride salts.[3] Isotopes[edit] Main article: Isotopes of ytterbium Natural ytterbium is composed of seven stable isotopes: 168Yb, 170Yb, 171Yb, 172Yb, 173Yb, 174Yb, and 176Yb, with 174Yb being the most abundant isotope, at 31.8% of the natural abundance). 27 radioisotopes have been observed, with the most stable ones being 169Yb with a half-life of 32.0 days, 175Yb with a half-life of 4.18 days, and 166Yb with a half-life of 56.7 hours. All of its remaining radioactive isotopes have half-lives that are less than two hours and most of these have half-lives are less than 20 minutes. Ytterbium also has 12 meta states, with the most stable being 169mYb (t½ 46 seconds).[8][9] The isotopes of ytterbium range in atomic weight from 147.9674 atomic mass unit (u) for 148Yb to 180.9562 u for 181Yb. The primary decay mode of ytterbium isotopes lighter than the most abundant stable isotope, 174Yb, is electron capture, and the primary decay mode for those heavier than 174Yb is beta decay. The primary decay products of ytterbium isotopes lighter than 174Yb are thulium isotopes, and the primary decay products of ytterbium isotopes with heavier than 174Yb are lutetium isotopes.[8][9] Occurrence[edit] Euxenite Ytterbium is found with other rare earth elements in several rare minerals. It is most often recovered commercially from monazite sand (0.03% ytterbium). The element is also found in euxenite and xenotime. The main mining areas are China, the United States, Brazil, India, Sri Lanka, and Australia; and reserves of ytterbium are estimated as one million tonnes. Ytterbium is normally difficult to separate from other rare earths, but ion-exchange and solvent extraction techniques developed in the mid- to late 20th century have simplified separation. Known compounds of ytterbium are rare and have not yet been well characterized. The abundance of ytterbium in the Earth's crust is about 3 mg/kg.[4] As an even-numbered lanthanide, in accordance with the Oddo-Harkins rule, ytterbium is significantly more abundant than its immediate neighbors, thulium and lutetium, which occur in the same concentrate at levels of about 0.5% each. The world production of ytterbium is only about 50 tonnes per year, reflecting the fact that ytterbium has few commercial applications.[4] Microscopic traces of ytterbium are used as a dopant in the Yb:YAG laser, a solid-state laser in which ytterbium is the element that undergoes stimulated emission of electromagnetic radiation.[10] Production[edit] It is somewhat difficult to separate ytterbium from other lanthanides due to its similar properties. As a result, the process is somewhat long. First, minerals such as monazite or xenotime are dissolved into various acids, such as sulfuric acid. Ytterbium can then be separated from other lanthanides by ion exchange, as can other lanthanides. The solution is then applied to a resin, which different lanthanides bond to in different matters. This is then dissolved using complexing agents, and due to the different types of bonding exhibited by the different lanthanides, it is possible to isolate the compounds.[11][12]

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