Tungsten: Wikis

  
  
  
  

Note: Many of our articles have direct quotes from sources you can cite, within the Wikipedia article! This article doesn't yet, but we're working on it! See more info or our list of citable articles.

Encyclopedia

From Wikipedia, the free encyclopedia

tantalumtungstenrhenium
Mo

W

Sg
Appearance
grayish white, lustrous
General properties
Name, symbol, number tungsten, W, 74
Element category transition metal
Group, period, block 66, d
Standard atomic weight 183.84g·mol−1
Electron configuration [Xe] 4f14 5d4 6s2[1]
Electrons per shell 2, 8, 18, 32, 12, 2 (Image)
Physical properties
Phase solid
Density (near r.t.) 19.25 g·cm−3
Liquid density at m.p. 17.6 g·cm−3
Melting point 3695 K, 3422 °C, 6192 °F
Boiling point 5828 K, 5555 °C, 10031 °F
Critical point 13892 K, MPa
Heat of fusion 52.31 kJ·mol−1
Heat of vaporization 806.7 kJ·mol−1
Specific heat capacity (25 °C) 24.27 J·mol−1·K−1
Vapor pressure
P/Pa 1 10 100 1 k 10 k 100 k
at T/K 3477 3773 4137 4579 5127 5823
Atomic properties
Oxidation states 6, 5, 4, 3, 2, 1, 0, −1, -2
(mildly acidic oxide)
Electronegativity 2.36 (Pauling scale)
Ionization energies 1st: 770 kJ·mol−1
2nd: 1700 kJ·mol−1
Atomic radius 139 pm
Covalent radius 162±7 pm
Miscellanea
Crystal structure body-centered cubic
Magnetic ordering paramagnetic[2]
Electrical resistivity (20 °C) 52.8 nΩ·m
Thermal conductivity (300 K) 173 W·m−1·K−1
Thermal expansion (25 °C) 4.5 µm·m−1·K−1
Young's modulus 411 GPa
Shear modulus 161 GPa
Bulk modulus 310 GPa
Poisson ratio 0.28
Mohs hardness 7.5
Vickers hardness 3430 MPa
Brinell hardness 2570 MPa
CAS registry number 7440-33-7
Most stable isotopes
Main article: Isotopes of tungsten
iso NA half-life DM DE (MeV) DP
180W 0.12% 1.8×1018 y α 2.516 176Hf
181W syn 121.2 d ε 0.188 181Ta
182W 26.50% 182W is stable with 108 neutrons
183W 14.31% 183W is stable with 109 neutrons
184W 30.64% 184W is stable with 110 neutrons
185W syn 75.1 d β 0.433 185Re
186W 28.43% 186W is stable with 112 neutrons

Tungsten (pronounced /ˈtʌŋstən/), also known as wolfram (/ˈwʊlfrəm/, WOOL-frəm), is a chemical element with the chemical symbol W and atomic number 74.

A steel-gray metal, tungsten is found in several ores, including wolframite and scheelite. It is remarkable for its robust physical properties, especially the fact that it has the highest melting point of all the non-alloyed metals and the second highest of all the elements after carbon. Also remarkable is its very high density of 19.3 times heavier than water, and 71% heavier than lead.[3] Tungsten is often brittle[4] and hard to work in its raw state; if pure, it can be cut with a hacksaw.[5]

The pure form is used mainly in electrical applications, but its many compounds and alloys have many applications, most notably in incandescent light bulb filaments, X-ray tubes (as both the filament and target), and superalloys.

Tungsten is the only metal from the third transition series that is known to occur in biomolecules, and is the heaviest element known to be used by living organisms.[6][7]

Contents

History

In 1781, Carl Wilhelm Scheele discovered that a new acid, tungstic acid, could be made from scheelite (at the time named tungstenite). Scheele and Torbern Bergman suggested that it might be possible to obtain a new metal by reducing this acid.[8] In 1783, José and Fausto Elhuyar found an acid made from wolframite that was identical to tungstic acid. Later that year, in Spain, the brothers succeeded in isolating tungsten by reduction of this acid with charcoal, and they are credited with the discovery of the element.[9][10]

In World War II, tungsten played a significant role in background political dealings. Portugal, as the main European source of the element, was put under pressure from both sides, because of its deposits of wolframite ore. Tungsten's resistance to high temperatures and its strength in alloys made it an important raw material for the weaponry industry.[11]

Etymology

The name "tungsten" (from the Nordic tung sten, meaning "heavy stone") is used in English, French, and many other languages as the name of the element. Tungsten was the old Swedish name for the mineral scheelite. The other name "wolfram" (or "volfram"), used for example in most European (especially Germanic and Slavic) languages, is derived from the mineral wolframite, and this is also the origin of its chemical symbol, W.[5] The name "wolframite" is derived from German "wolf rahm" ("wolf soot" or "wolf cream"), the name given to tungsten by Johan Gottschalk Wallerius in 1747. This, in turn, derives from "Lupi spuma", the name Georg Agricola used for the element in 1546, which translates into English as "wolf's froth" or "cream" (the etymology is not entirely certain), and is a reference to the large amounts of tin consumed by the mineral during its extraction.[12]

Characteristics

Physical

In its raw form, tungsten is a steel-gray metal that is often brittle and hard to work, but, if pure, it can be worked easily.[5] It is worked by forging, drawing, extruding or sintering. Of all metals in pure form, tungsten has the highest melting point (3,422 °C, 6,192 °F), lowest vapor pressure and (at temperatures above 1,650 °C, 3,000 °F) the highest tensile strength.[13] Tungsten has the lowest coefficient of thermal expansion of any pure metal. The low thermal expansion and high melting point and strength of tungsten are due to strong covalent bonds formed between tungsten atoms by the 5d electrons.[14] Alloying small quantities of tungsten with steel greatly increases its toughness.[3]

Isotopes

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[15] to do so with a half-life of (1.8 ± 0.2)×1018 yr; on average, this yields about two alpha decays of 180W in one gram of natural tungsten per year.[16] The other naturally occurring isotopes have not been observed to decay, constraining their half-lives to be[16]

182W, T1/2 > 8.3×1018 years
183W, T1/2 > 29×1018 years
184W, T1/2 > 13×1018 years
186W, T1/2 > 27×1018 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.[16] All of the remaining radioactive isotopes have half-lives of less than 3 hours, and most of these have half-lives below 8 minutes.[16] Tungsten also has 4 meta states, the most stable being 179mW (T½ 6.4 minutes).

Chemical

Main article: Tungsten compounds

Elemental tungsten resists attack by oxygen, acids, and alkalis.[17]

The most common formal oxidation state of tungsten is +6, but it exhibits all oxidation states from −2 to +6.[17][18] 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 and are some of the hardest carbides, with a melting point of 2770 °C for WC and 2780 °C for W2C. WC is an efficient electrical conductor, but W2C is less so. Tungsten carbide behaves similarly to unalloyed tungsten and is resistant to chemical attack, although it reacts strongly with chlorine to form tungsten hexachloride (WCl6).[3]

Aqueous tungstate solutions are noted for the formation of 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, W7O6–24, which over time converts to the less soluble "paratungstate B" anion, H2W12O10–42.[19] Further acidification produces the very soluble metatungstate anion, H2W12O6–40, 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.

Biological role

Tungsten, at atomic number 74, is the heaviest element known to be used by any living organism, with the next heaviest being iodine (Z = 53). Tungsten has not been found to be necessary or used in eukaryotes, but it is an essential nutrient for some bacteria. 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 reduce free carboxylic acids to aldehydes.[20] 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.[21] One of the enzymes in the oxidoreductase family which sometimes employ tungsten (bacterial formate dehydrogenate H) is known to use a selenium-molybdenum version of molybdopterin.[22] 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.[23]

Other effects on biochemistry

In soil, tungsten metal oxidizes to the tungstate anion. It may substitute for molybdenum in certain enzymes, and in such cases the resulting enzyme in eukaryotes would presumably be inert. The soil's chemistry determines how the tungsten polymerizes; alkaline soils cause monomeric tungstates; acidic soils cause polymeric tungstates.[24]

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.[25]

Tungsten has been studied as a biological copper antagonist in the same role as molybdenum. It has been found that tetrathiotungstates may be used as biological copper chelation chemicals in a role similar to tetrathiomolybdates.[26]

Production

Wolframite
Tungsten output in 2005

Tungsten is found in the minerals wolframite (iron-manganese tungstate, FeWO4/MnWO4), scheelite (calcium tungstate, (CaWO4), ferberite (FeWO4) and hübnerite (MnWO4). These are mined and used to produce about 37,400 tonnes of tungsten concentrates per year in 2000.[27] China produced over 75% of this total, with most of the remaining production coming from Austria, Bolivia, Portugal, and Russia.[27]

Tungsten is extracted from its ores in several stages. The ore is eventually converted to tungsten(VI) oxide (WO3), which is heated with hydrogen or carbon to produce powdered tungsten.[8] It can be used in that state or pressed into solid bars.

Tungsten can also be extracted by hydrogen reduction of WF6:

WF6 + 3 H2 → W + 6 HF

or pyrolytic decomposition:[28]

WF6 → W + 3 F2 (ΔHr = +)

Tungsten prices are tracked on the London Metal Exchange. The price for pure metal is around $20,075 per tonne as of October 2008.[29]

Applications

Close-up of a tungsten filament inside a halogen lamp.

Because it retains its strength at high temperatures and has a high melting point, elemental tungsten is used in many high-temperature applications,[30] such as light bulb, cathode-ray tube, and vacuum tube filaments, heating elements, and rocket engine nozzles.[5] Its high melting point also makes tungsten suitable for aerospace and high-temperature uses such as electrical, heating, and welding applications, notably in the gas tungsten arc welding process [also called tungsten inert gas (TIG) welding].

Because of its conductive properties and relative chemical inertia, tungsten is also used in electrodes, and in the emitter tips in electron-beam instruments that use field emission guns, such as electron microscopes. In electronics, tungsten is used as an interconnect material in integrated circuits, between the silicon dioxide dielectric material and the transistors. It is used in metallic films, which replace the wiring used in conventional electronics with a coat of tungsten (or molybdenum) on silicon.[28]

The electronic structure of tungsten makes it one of the main sources for X-ray targets,[31] and also for shielding from high-energy radiations (such as in the radiopharmaceutical industry for shielding radioactive samples of FDG). Tungsten powder is used as a filler material in plastic composites, which are used as a nontoxic substitute for lead in bullets, shot, and radiation shields. Since this element's thermal expansion is similar to borosilicate glass, it is used for making glass-to-metal seals.[13]

The hardness and density of tungsten are applied in obtaining heavy metal alloys. A good example is high speed steel, which may contain as much as 18% tungsten.[32] Superalloys containing tungsten, such as Hastelloy and Stellite, are used in turbine blades and wear-resistant parts and coatings. Applications requiring its high density include heat sinks, weights, counterweights, ballast keels for yachts, tail ballast for commercial aircraft, and as ballast in race cars for NASCAR and Formula One. It is an ideal material to use as a dolly for riveting, where the mass necessary for good results can be achieved in a compact bar. In armaments, tungsten, usually alloyed with nickel and iron or cobalt to form heavy alloys, is used in kinetic energy penetrators as an alternative to depleted uranium but may also be used in cannon shells, grenades and missiles to create supersonic shrapnel. High-density alloys of tungsten with nickel, copper or iron are used in high-quality darts[33] (to allow for a smaller diameter and thus tighter groupings) or for fishing lures (tungsten beads allow the fly to sink rapidly). Some types of strings for musical instruments are wound with tungsten wires. Its density, similar to that of gold, allows tungsten to be used in jewelry as an alternative to gold or platinum.[5][34] Its hardness makes it ideal for rings that will resist scratching, are hypoallergenic, and will not need polishing, which is especially useful in designs with a brushed finish.[35]

Tungsten compounds are used in catalysts, inorganic pigments (e.g. tungsten oxides), and as high-temperature lubricants (tungsten disulfide). Tungsten carbide (WC) is used to make wear-resistant abrasives and cutters and knives for drills, circular saws, milling and turning tools used by the metalworking, woodworking, mining, petroleum and construction industries[3] and accounts for about 60% of current tungsten consumption.[36] Tungsten oxides are used in ceramic glazes and calcium/magnesium tungstates are used widely in fluorescent lighting, while tungsten halogen bulbs are frequently used to light indoor photo shoots, and special negative films exist to take advantage of tungsten's unique disentangling properties. Crystal tungstates are used as scintillation detectors in nuclear physics and nuclear medicine. Other salts that contain tungsten are used in the chemical and tanning industries.[13]

Precautions

The data concerning the toxicity of tungsten is limited, but cases of intoxication by tungsten compounds are known, the lethal dose is estimated to be between 500 mg/kg and 5 g/kg for humans.[37][38] Tungsten is known to generate seizure and renal failure with acute tubular necrosis.[39][40][41]

The effects of tungsten within the environment are essentially unknown, a concern that has arisen in response to increasingly widespread use of the material as a fishing sinker, some of which are inevitably lost into water bodies. The same unknown variable applies whenever tungsten may be deposited into the environment, either knowingly or inadvertently.[42]

See also

References

  1. ^ "Why does Tungsten not 'Kick' up an electron from the s sublevel ?". http://www.madsci.org/posts/archives/2000-02/951518136.Ch.r.html. Retrieved 2008-06-15. 
  2. ^ Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics 81st edition, CRC press.
  3. ^ a b c d Daintith, John (2005). Facts on File Dictionary of Chemistry, 4th ed.. New York: Checkmark Books. 
  4. ^ Lassner, Erik; Schubert, Wolf-Dieter (1999). "low temperature brittleness". Tungsten: properties, chemistry, technology of the element, alloys, and chemical compounds. Springer. p. 256. ISBN 9780306450532. http://books.google.com/books?id=foLRISkt9gcC&pg=PA20. 
  5. ^ a b c d e Stwertka, Albert (2002). A Guide to the elements, 2nd ed.. New York: Oxford University Press. 
  6. ^ McMaster, J. and Enemark, John H (1998). "The active sites of molybdenum- and tungsten-containing enzymes". Current Opinion in Chemical Biology 2 (2): 201–207. doi:10.1016/S1367-5931(98)80061-6. 
  7. ^ Hille, Russ (2002). "Molybdenum and tungsten in biology". Trends in Biochemical Sciences 27 (7): 360–367. doi:10.1016/S0968-0004(02)02107-2. 
  8. ^ a b Saunders, Nigel (February 2004). Tungsten and the Elements of Groups 3 to 7 (The Periodic Table). Chicago, Illinois: Heinemann Library. ISBN 1403435189. 
  9. ^ "ITIA Newsletter" (PDF). International Tungsten Industry Association. June 2005. http://www.itia.info/FileLib/ITIA_Newsletter_June05.pdf. Retrieved 2008-06-18. 
  10. ^ "ITIA Newsletter" (PDF). International Tungsten Industry Association. December 2005. http://www.itia.info/FileLib/ITIA_Newsletter_December05.pdf. Retrieved 2008-06-18. 
  11. ^ Stevens, Donald G. (1999). "World War II Economic Warfare: The United States, Britain, and Portuguese Wolfram". The Historian (Questia). http://www.questia.com/googleScholar.qst;jsessionid=LY1PyzmCc1D256Gvh5wpbhxKyTyvcm2FHpMwpcs2wW2XyytCh4pW!956463030?docId=5001286099. 
  12. ^ van der Krogt, Peter. "Wolframium Wolfram Tungsten". Elementymology & Elements Multidict. http://elements.vanderkrogt.net/element.php?sym=W. Retrieved 2010-03-11. 
  13. ^ a b c C. R. Hammond (2004). The Elements, in Handbook of Chemistry and Physics 81st edition. CRC press. ISBN 0849304857. 
  14. ^ Erik Lassner, Wolf-Dieter Schubert (1999). Tungsten: properties, chemistry, technology of the element, alloys, and chemical compounds. Springer. p. 9. ISBN 0306450534. http://books.google.com/books?id=foLRISkt9gcC&pg=PA9. 
  15. ^ C. Cozzini et al. (2004). "Detection of the natural α decay of tungsten". Phys. Rev. C 70: 064606. doi:10.1103/PhysRevC.70.064606. http://arxiv.org/abs/nucl-ex/0408006. 
  16. ^ a b c d Alejandro Sonzogni. "Interactive Chart of Nuclides". National Nuclear Data Center: Brookhaven National Laboratory. http://www.nndc.bnl.gov/chart/. Retrieved 2008-06-06. 
  17. ^ a b Emsley, John E. (1991). The elements, 2nd ed.. New York: Oxford University Press. 
  18. ^ Morse, P. M.; Shelby, Q. D.; Kim, D. Y.; Girolami, G. S. (2008). "Ethylene Complexes of the Early Transition Metals: Crystal Structures of [HfEt4(C2H4)2−] and the Negative-Oxidation-State Species [TaHEt(C2H4)33−] and [WH(C2H4)43−]". Organometallics 27: 984–993. doi:10.1021/om701189e. 
  19. ^ Smith, Bradley J. (2000). "Quantitative Determination of Sodium Metatungstate Speciation by 183W N.M.R. Spectroscopy". Australian Journal of Chemistry (CSIRO) 53 (12). http://www.publish.csiro.au/paper/CH00140.htm. Retrieved 2008-06-17. 
  20. ^ Lassner, Erik (1999). Tungsten: Properties, Chemistry, Technology of the Element, Alloys and Chemical Compounds. Springer. pp. 409–411. ISBN 0306450534. http://books.google.com/books?id=foLRISkt9gcC&pg=PA409&lpg=PA409&dq=tungsten+nutrient+organisms&source=web&ots=-rtHF9sWBY&sig=CoCD7Wp0HS-QRzQEoiPCisLaP04&hl=en&sa=X&oi=book_result&resnum=1&ct=result. 
  21. ^ Stiefel, E. I. (1998). "Transition metal sulfur chemistry and its relevance to molybdenum and tungsten enzymes". Pure & Appl. Chem. 70 (4): 889–896. doi:10.1351/pac199870040889. http://media.iupac.org/publications/pac/1998/pdf/7004x0889.pdf. 
  22. ^ Khangulov, S. V. et al. (1998). "Selenium-Containing Formate Dehydrogenase H from Escherichia coli: A Molybdopterin Enzyme That Catalyzes Formate Oxidation without Oxygen Transfer". Biochemistry 37: 3518–3528. doi:10.1021/bi972177k. 
  23. ^ Schrader, Thomas; Rienhofer, Annette; Andreesen, Jan R. (1999). "Selenium-containing xanthine dehydrogenase from Eubacterium barkeri". Eur. J. Biochem. 264 (3): 862–71. doi:10.1046/j.1432-1327.1999.00678.x. 
  24. ^ Chemical & Engineering News, 19 Jan. 2009, "Unease over Tungsten", p. 63
  25. ^ Inouye, L. S. et al. (2006). "Tungsten effects on survival, growth, and reproduction in the earthworm, eisenia fetida". Environmental Toxicology & Chemistry 25 (3): 763. doi:10.1897/04-578R.1. 
  26. ^ McQuaid A; Lamand M; Mason J. (1994). "Thiotungstate-copper interactions II. The effects of tetrathiotungstate on systemic copper metabolism in normal and copper-treated rats". J Inorg Biochem 53: 205. doi:10.1016/0162-0134(94)80005-7. 
  27. ^ a b Shedd, Kim B. (2000). "Tungsten" (PDF). United States Geological Survey. http://minerals.usgs.gov/minerals/pubs/commodity/tungsten/680400.pdf. Retrieved 2008-06-18. 
  28. ^ a b Schey, John A. (1987). Introduction to Manufacturing Processes, 2nd ed.. McGraw-Hill, Inc. 
  29. ^ "Metal Bulletin". http://www.mineralprices.com. Retrieved 2009-05-05. 
  30. ^ DeGarmo, E. Paul (1979). Materials and Processes in Manufacturing, 5th ed.. New York: MacMillan Publishing. 
  31. ^ Hasz, Wayne Charles et al. "X-ray target" U.S. Patent 6,428,904, August 6, 2002
  32. ^ "Tungsten Applications - Steel". azom.com. 2000–2008. http://www.azom.com/details.asp?ArticleID=1264. Retrieved 2008-06-18. 
  33. ^ Turrell, Kerry (2004). Tungsten. Marshall Cavendish. p. 24. ISBN 0761415483. http://books.google.com/books?id=QUyO7jgvOQUC&pg=PA24. 
  34. ^ Hesse, Rayner W. (2007). "tungsten". Jewelrymaking through history : an encyclopedia. Westport, Conn.: Greenwood Press. pp. 190–192. ISBN 9780313335075. http://books.google.com/books?id=DIWEi5Hg93gC&pg=PA190. 
  35. ^ Gray, Theo (March 14, 2008). "How to Make Convincing Fake-Gold Bars". Popular Science. http://www.popsci.com/diy/article/2008-03/how-make-convincing-fake-gold-bars. Retrieved 2008-06-18. 
  36. ^ "The Canadian Encyclopaedia". http://www.thecanadianencyclopedia.com/index.cfm?PgNm=TCE&Params=A1ARTA0008159. Retrieved 2009-05-05. 
  37. ^ Koutsospyros, A.; Braida, W.; Christodoulatos, C.; Dermatas, D.; Strigul, N. (2006). "A review of tungsten: From environmental obscurity to scrutiny". Journal of Hazardous Materials 136 (1): 1–19. doi:10.1016/j.jhazmat.2005.11.007. PMID 16343746. 
  38. ^ Masten, Scott (2003). "Tungsten and Selected Tungsten Compounds — Review of Toxicological Literature". National Institute of Environmental Health Sciences. http://ntp.niehs.nih.gov/ntp/htdocs/Chem_Background/ExSumPdf/tungsten.pdf. Retrieved 2009-03-19. 
  39. ^ Marquet, P. et al. (1996). "A soldier who had seizures after drinking quarter of a litre of wine.". Lancet 348 (9034): 1070. doi:10.1016/S0140-6736(96)05459-1. PMID 8874460. 
  40. ^ Lison, D. et al. (1997). "Toxicity of tungsten.". Lancet 349 (9044): 58–9. PMID 8988138. 
  41. ^ Marquet, P. et al. (1997). "Tungsten determination in biological fluids, hair and nails by plasma emission spectrometry in a case of severe acute intoxication in man.". Journal of forensic sciences 42 (3): 527–30. PMID 9144946. 
  42. ^ Strigul, N; Koutsospyros, A; Arienti, P; Christodoulatos, C; Dermatas, D; Braida, W (Oct 2005). "Effects of tungsten on environmental systems.". Chemosphere 61 (2): 248–58. doi:10.1016/j.chemosphere.2005.01.083. ISSN 0045-6535. PMID 16168748. 

External links


1911 encyclopedia

Up to date as of January 14, 2010
(Redirected to Database error article)

From LoveToKnow 1911

(There is currently no text in this page)


Wiktionary

Up to date as of January 15, 2010
(Redirected to tungsten article)

Definition from Wiktionary, a free dictionary

Chemical element
W Previous: tantalum (Ta)
Next: rhenium (Re)

Contents

English

Alternative spellings

  • tungstenum

Etymology

Swedish and Danish tung heavy, + sten stone (although neither language uses "tungsten" as the name of the element)

Noun

Singular
tungsten

Plural
uncountable

tungsten (uncountable)

Wikipedia-logo.png
Wikipedia has an article on:

Wikipedia

  1. a metallic chemical element (symbol W) with an atomic number of 74. The symbol is derived from the Latin word wolframium.

Synonyms

Derived terms

  • eka-tungsten
  • ferrotungsten
  • tungstenane
  • tungsten carbide
  • tungsten disulfide, tungsten disulphide
  • tungsten fluoride
  • tungsten-halogen lamp
  • tungsten hexafluoride
  • tungstenic
  • tungsten iodide
  • tungsteniferous
  • tungstenite
  • tungstenitic
  • tungsten lamp
  • tungsten oxide
  • tungsten-steel
  • tungsten sulfide, tungsten sulphide
  • tungsten trioxide
  • tungstic
  • tungstite
  • tungsto-
  • tungstous

Related terms

Translations

External links

For more information refer to: http://elements.vanderkrogt.net/elem/w.html (A lot of the translations were taken from that site with permission from the author)

See also


Simple English

[[File:|thumb|Granules of tungsten in a glass vial.]] Tungsten (sometimes named wolfram) is a chemical element. It has the chemical symbol W. It has the atomic number 74. It is a metal. The colour of the metal is steel-gray to white. In chemistry it is placed in a group of metal elements named the transition metals. Tungsten is found in several ores. Two ores which have tungsten in them are wolframite and scheelite.

Tungsten has a higher melting point than any other non-alloy that exists. The pure form (only tungsten) is mainly used for electrical uses. Its compounds and alloys are used for many things. Their most well known use is in light bulb filaments. It is also used as the filament and target in most X-ray tubes and also in superalloys. It is also used in glass to metal seals.








Got something to say? Make a comment.
Your name
Your email address
Message