- Also called:
- wolfram
- Key People:
- Fausto Elhuyar
- Irving Langmuir
- William D. Coolidge
tungsten
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What is tungsten?
Tungsten (W), also known as wolfram in some countries, is a chemical element with atomic number 74 and atomic weight 183.85. This strong, refractory metal is in Group 6 of the periodic table and has the highest melting point of all metals at 3,410 °C (6,170 °F).
Tungsten is used to strengthen steel, create hard cutting edges for tools, and produce filaments for incandescent lamps. The majority of the world's tungsten is produced in China.
Tungsten occurs in minerals such as scheelite and wolframite. The metal was first isolated in 1783 by Spanish chemists who reduced tungstic oxide with charcoal.
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What is tungsten's chemical symbol and atomic number?
The chemical symbol for tungsten is W, and its atomic number is 74. The name tungsten has been used for the metal since its discovery, though Jöns Jacob Berzelius's symbol W prevails.
Tungsten is a strong, refractory metal used to increase hardness and strength in steels and in lamp filaments. It has a high melting point of 3,410 °C (6,170 °F) and is highly conductive to electricity.
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Where is tungsten found in nature?
Tungsten is about as abundant as tin or molybdenum in Earth’s crust. It does not occur as a free metal but is found in ores such as tungstates like scheelite (CaWO_4), stolzite (PbWO_4), and wolframite (a solid solution of ferrous tungstate, FeWO_4, and manganous tungstate, MnWO_4).
Tungsten deposits are associated with metamorphic and granitic igneous rocks. The most important mines are in China, which holds about 50% of the world's reserves. Mines are also located in Russia, around Lake Baikal and in the northern Caucasus, as well as in Kazakhstan. South Korea, Canada’s Northwest Territories, and Chojlla, Bolivia, also have tungsten mines.
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What are some important physical properties of tungsten?
Tungsten (W) is a chemical element with atomic number 74 and atomic weight 183.85. It has a high melting point of 3,410 °C (6,170 °F) and a boiling point of 5,660 °C (10,220 °F). Its density is 19.3 grams/cm3 at 20 °C (68 °F).
Tungsten has high conductivity for electricity and the lowest coefficient of linear thermal expansion (4.43 × 10−6 per °C at 20 °C [68 °F]). It is resistant to acids but can be attacked by alkaline oxidizing melts. The metal is brittle at room temperature but ductile and strong at elevated temperatures.
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What are common uses of tungsten in everyday life and industry?
Tungsten, also known as wolfram, is a strong, refractory metal with the highest melting point of all metals. Its unique properties make it useful in everyday life and various industries.
- Incandescent lamps Tungsten is used to make filaments for incandescent light bulbs because it can operate at high temperatures and emit a whiter light.
- Alloying agent Tungsten is added to tool steels, superalloys, and refractory alloys to increase their hardness and strength. Cobalt-chromium-tungsten alloys are used for wear-resistant valves, bearings, and cutting tools.
- Cutting tools and abrasives Tungsten carbide, a compound of tungsten and carbon, is used to make hard cutting tools, abrasives, and dies.
- Other uses Tungsten is also used for electrical contacts, electron emitters, rocket nozzles, and dyes.
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Why is tungsten valued for making lightbulb filaments and cutting tools?
Tungsten is valued in lightbulb filaments and cutting tools for its unique properties. It has the highest melting point of all metals at 3,410 °C (6,170 °F) and high conductivity for electricity, making it suitable for incandescent lamp filaments that operate at high temperatures to produce whiter light.
Tungsten carbides are valued for cutting tools because of their hardness and resistance to wear. Tungsten is also added to tool steels to allow tools to operate at higher speeds.
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tungsten (W), chemical element, an exceptionally strong refractory metal of Group 6 (VIb) of the periodic table, used in steels to increase hardness and strength and in lamp filaments.
Tungsten metal was first isolated (1783) by the Spanish chemists and mineralogists Juan José and Fausto Elhuyar by charcoal reduction of the oxide (WO3) derived from the mineral wolframite. Earlier (1781) the Swedish chemist Carl Wilhelm Scheele had discovered tungstic acid in a mineral now known as scheelite, and his countryman Torbern Bergman concluded that a new metal could be prepared from the acid. The names tungsten and wolfram have been used for the metal since its discovery, though everywhere Jön Jacob Berzelius’s symbol W prevails. In British and American usage, tungsten is preferred; in Germany and a number of other European countries, wolfram is accepted.
| atomic number | 74 |
|---|---|
| atomic weight | 183.85 |
| melting point | 3,410 °C (6,152 °F) |
| boiling point | 5,660 °C (10,220 °F) |
| density | 19.3 grams/cm3 at 20 °C (68 °F) |
| oxidation states | +2, +3, +4, +5, +6 |
| electron configuration | [Xe]4f145d46s2 |
Occurrence, properties, and uses
The amount of tungsten in Earth’s crust is estimated to be 1.5 parts per million, or about 1.5 grams per ton of rock. China is the dominant producer of tungsten; in 2016 it produced over 80 percent of total tungsten mined, and it contained nearly two-thirds of the world’s reserves. Vietnam, Russia, Canada, and Bolivia produce most of the remainder. Tungsten does not occur as a free metal. It is about as abundant as tin or as molybdenum, which it resembles, and half as plentiful as uranium. Although tungsten occurs as tungstenite—tungsten disulfide, WS2—the most important ores in this case are the tungstates such as scheelite (calcium tungstate, CaWO4), stolzite (lead tungstate, PbWO4), and wolframite—a solid solution or a mixture or both of the isomorphous substances ferrous tungstate (FeWO4) and manganous tungstate (MnWO4).
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For tungsten the ores are concentrated by magnetic and mechanical processes, and the concentrate is then fused with alkali. The crude melts are leached with water to give solutions of sodium tungstate, from which hydrous tungsten trioxide is precipitated upon acidification, and the oxide is then dried and reduced to metal with hydrogen.
Tungsten is rather resistant to attack by acids, except for mixtures of concentrated nitric and hydrofluoric acids, and it can be attacked rapidly by alkaline oxidizing melts, such as fused mixtures of potassium nitrate and sodium hydroxide or sodium peroxide; aqueous alkalies, however, are without effect. It is inert to oxygen at normal temperature but combines with it readily at red heat, to give the trioxides, and is attacked by fluorine at room temperature, to give the hexafluorides.
Tungsten metal has a nickel-white to grayish lustre. Among metals it has the highest melting point, at 3,410 °C (6,170 °F), the highest tensile strength at temperatures of more than 1,650 °C (3,002 °F), and the lowest coefficient of linear thermal expansion (4.43 × 10−6 per °C at 20 °C [68 °F]). Tungsten is ordinarily brittle at room temperature. Pure tungsten can, however, be made ductile by mechanical working at high temperatures and can then be drawn into very fine wire. Tungsten was first commercially employed as a lamp filament material and thereafter used in many electrical and electronic applications. It is used in the form of tungsten carbide for very hard and tough dies, tools, gauges, and bits. Much tungsten goes into the production of tungsten steels, and some has been used in the aerospace industry to fabricate rocket-engine nozzle throats and leading-edge reentry surfaces. (For information on the mining, recovery, and applications of tungsten, see tungsten processing.)
Natural tungsten is a mixture of five stable isotopes: tungsten-180 (0.12 percent), tungsten-182 (26.50 percent), tungsten-183 (14.31 percent), tungsten-184 (30.64 percent), and tungsten-186 (28.43 percent). Tungsten crystals are isometric and, by X-ray analysis, are seen to be body-centred cubic.
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Compounds
Chemically, tungsten is relatively inert. Compounds have been prepared, however, in which the element has oxidation states from 0 to +6. The states above +2, especially +6, are most common. In the +4, +5, and +6 states, tungsten forms a variety of complexes.
The most important tungsten compound is tungsten carbide (WC), which is noted for its hardness (9.5 on the Mohs scale, where the maximum, diamond, is 10). It is used alone or in combination with other metals to impart wear-resistance to cast iron and the cutting edges of saws and drills. Tungsten also forms hard, refractory, and chemically inert interstitial compounds with boron, nitrogen, and silicon upon direct reaction with those elements at high temperatures.