AskDefine | Define tungsten

Dictionary Definition

tungsten n : a heavy gray-white metallic element; the pure form is used mainly in electrical applications; it is found in several ores including wolframite and scheelite [syn: wolfram, W, atomic number 74]

User Contributed Dictionary

English

Alternative spellings

Etymology

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

Noun

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

Synonyms

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)

Extensive Definition

|- | 182W || 26.50% || colspan="4" | W is stable with 108 neutrons |- | 183W || 14.31% || colspan="4" | W is stable with 109 neutrons |- | 184W || 30.64% || colspan="4" | W is stable with 110 neutrons |- | 186W || 28.43% || colspan="4" | W is stable with 112 neutrons Tungsten (), also known as wolfram (/ˈwʊlfrəm/), is a chemical element that has the 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. Tungsten is often brittle and hard to work in its raw state; however, if pure, it can be cut with a hacksaw. The pure form is used mainly in electrical applications, but its many compounds and alloys are used in many applications, most notably in light bulb filaments, X-ray tubes (as both the filament and target), and superalloys. Tungsten is also the only metal from the third transition series that is known to occur in biomolecules.

Etymology

"Tungsten" (from the Swedish tung sten, meaning "heavy stone") is commonly accepted as the name of the material, although some chemists (primarily in Germany but also e.g. in Sweden) refer to it as "wolfram", from its ore wolframite. The name "wolframite" was derived from "volf rahm", the word Johan Gottschalk Wallerius used to refer to it in 1747. This, in turn, was translated from "Lupi spuma", the word Georg Agricola used to refer to the element in 1546. Its English translation is "wolf's froth", so named because the mineral consumed a large amount of tin in its extraction. Its chemical symbol, W, is derived from wolfram as well. Tungsten has the lowest coefficient of thermal expansion of any pure metal. Alloying small quantities of tungsten with steel greatly increases its toughness.
182W, T1/2 > 8.3·1018 yr;
183W, T1/2 > 29·1018 yr;
184W, T1/2 > 13·1018 yr;
186W, T1/2 > 27·1018 yr.
On average, two alpha decays of 180W occur in one gram of natural tungsten per year.
27 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 and 178W with a half-life of 21.6 days. All of the remaining radioactive isotopes have half-lives of less than 24 hours, and most of these have half-lives that are less than 8 minutes. Tungsten also has 4 meta states, the most stable being 179mW (t½ 6.4 minutes).

Chemical properties

Tungsten resists attack by oxygen, acids, and alkalis.

Compounds

''Main article: Tungsten compounds
The most common formal oxidation state of tungsten is +6, but it exhibits all oxidation states from -1 to +6. Sixteen recent cases of cancer in children were discovered in the Fallon area, which has now been identified as a cancer cluster (however, the majority of the cancer victims are not longtime residents of Fallon). Dr. Carol H. Rubin, a branch chief at the CDC, said data demonstrating a link between tungsten and leukemia is not available at present.

Applications

Because of its ability to produce hardness at high temperatures and its high melting point (the second highest of any known element), tungsten is used in many high-temperature applications. These include light bulb, cathode-ray tube, and vacuum tube filaments, as well as heating elements and nozzles on rocket engines.
In metal alloys, high speed steel contains tungsten; some tungsten steels contain as much as 18% tungsten. Superalloys containing tungsten are used in turbine blades and wear resistant parts and coatings. Examples are Hastelloy and Stellite.
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.

Production

Tungsten is found in the minerals wolframite (iron-manganese tungstate, FeWO4/MnWO4), scheelite (calcium tungstate, (CaWO4), ferberite and hübnerite. There are major deposits of these minerals in China (with about 57% world share), Russia, Austria and Portugal, reports the British Geological Survey. Approximately 75% of the world's tungsten resources are thought to exist in China, It can be used in that state or converted into solid bars.
Tungsten can also be extracted by hydrogen reduction of WF6 (WF6 + 3H2 = W + 6HF) or pyrolytic decomposition (WF6 + energy = W + 3F2).
In World War II, tungsten played an enormous role in background political dealings. Portugal, as the main European source of the element, was put under pressure from both sides, because of its sources of wolframite ore. The resistance to high temperatures, as well as the extreme strength of its alloys, made the metal into a very important raw material for the weaponry industry.

References

  • DC/AC Circuits and Electronics: Principles & Applications by Robert K. Herrick, Published by Delmar Learning 2003 for Purdue University

External links

tungsten in Arabic: تنجستن
tungsten in Azerbaijani: Volfram
tungsten in Belarusian: Вальфрам
tungsten in Bosnian: Volfram
tungsten in Bulgarian: Волфрам
tungsten in Catalan: Tungstè
tungsten in Czech: Wolfram
tungsten in Corsican: Tungstenu
tungsten in Welsh: Twngsten
tungsten in Danish: Wolfram
tungsten in German: Wolfram
tungsten in Estonian: Volfram
tungsten in Modern Greek (1453-): Βολφράμιο
tungsten in Spanish: Wolframio
tungsten in Esperanto: Volframo
tungsten in Persian: تنگستن
tungsten in French: Tungstène
tungsten in Friulian: Tungsten
tungsten in Manx: Tungsten
tungsten in Korean: 텅스텐
tungsten in Armenian: Վոլֆրամ
tungsten in Croatian: Volfram
tungsten in Ido: Wolframo
tungsten in Indonesian: Wolfram
tungsten in Icelandic: Volfram
tungsten in Italian: Tungsteno
tungsten in Hebrew: טונגסטן
tungsten in Kurdish: Tûngsten
tungsten in Latin: Wolframium
tungsten in Latvian: Volframs
tungsten in Luxembourgish: Wolfram
tungsten in Lithuanian: Volframas
tungsten in Lojban: jarjinme
tungsten in Hungarian: Volfrám
tungsten in Marathi: टंग्स्टन
tungsten in Dutch: Wolfraam
tungsten in Japanese: タングステン
tungsten in Norwegian: Wolfram
tungsten in Norwegian Nynorsk: Wolfram
tungsten in Low German: Wolfram
tungsten in Polish: Wolfram
tungsten in Portuguese: Tungstênio
tungsten in Romanian: Wolfram (element)
tungsten in Russian: Вольфрам
tungsten in Simple English: Tungsten
tungsten in Slovak: Volfrám
tungsten in Slovenian: Volfram
tungsten in Serbian: Волфрам
tungsten in Serbo-Croatian: Volfram
tungsten in Finnish: Volframi
tungsten in Swedish: Volfram
tungsten in Tamil: டங்க்ஸ்டன்
tungsten in Thai: ทังสเตน
tungsten in Vietnamese: Volfram
tungsten in Tajik: Волфрам
tungsten in Turkish: Volfram
tungsten in Ukrainian: Вольфрам
tungsten in Chinese: 钨
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