Laura Speirs June 13, 2011 Professor Nalley Tungsten Paper Tungsten Tungsten is a gray-white metallic element that is stable and is very resistant to acids and bases. It does, however, oxidize in air, especially at higher temperatures Tungsten was discovered by Juan Jose and Fausto Elhuyar, Spanish chemists and brothers, in 1783 in samples of the mineral wolframite ((Fe, Mn)WO4). Tungsten was named from the Swedish words “tung sten” meaning “heavy stone. ” Tungsten’s chemical symbol comes from its eariler, Germanic name, Wolfram. The name Wolfram comes from the mineral wolframite, in which it was discovered.
Wolframite means “the devourer of tin” since the mineral interferes with the smelting of tin. [2]That’s why tungsten’s symbol is a W. Tungsten is retrieved from the ore minerals scheelite (CaWO4) and wolframite ((Fe,Mn)WO4). Of the world’s tungsten reserves, nearly half are found in China. Canada and Russia also have large reserves. A significant amount of tungsten is recovered through recycling of scrap tungsten products.
Tungsten is classified as a “Transition Metal” which is located in Groups 3 – 12 of the Periodic Table.
An element classified as transition metals are ductile, malleable, and able to conduct electricity and heat. Tungsten is mixed with carbon to make a very strong, very resistant material called tungsten carbide. Tungsten carbide is used to make cutting tools and wear-resistant tools for metalworking, drilling for oil and gas, mining, and construction. These applications account for more than 60% of the tungsten consumed in the US each year. Because tungsten has such a very high melting point and low vapor pressure, tungsten is used in high temperature situations.
It does, however, oxidize in air, especially at higher temperatures.
It has the highest melting temperature of any metal (3422 degrees C, 6192 degrees F), and the second highest of all elements (Carbon is highest). For instance, the filaments in light bulbs are made of tungsten. It is used in other applications in electronics as well. When added to steel, tungsten increases its strength. It is alloyed (mixed with) other metals to make “super alloys” which have special physical properties of high strength and heat resistance. Some of the applications for such super alloys are in turbine engines for jet aircraft and energy generation.
Other alloys bearing tungsten are used for armaments, heat sinks, radiation shielding, weights and counterweights, wear-resistant parts and coatings. Tungsten is also useful for glass-to-metal seals since the thermal expansion is about the same as borosilicate glass. Tungsten and its alloys are used extensively for filaments for electric lamps, electron and television tubes, for metal evaporation work, electrical contact points for car distributors, X-ray targets, windings and heating elements for electrical furnaces, and missile and high-temperature applications.
More recently tungsten has found use in jewelry where its hardness and scratch resistance make it highly desirable. There are so many more things that are made with or out of tungsten that its too many too list. Tungsten is the only material used to make light bulb filaments, because tungsten has the highest melting point of any metal. [3] Experiments are being done with ceramic and ceramics mixed with metals to create alternative cutting materials. Cemented carbide made with tungsten carbide is still preferred to these materials.
Tungsten as a biological metal is a most unlikely choice; they are indeed very few elements of selection for functional purposes of elements atomic number higher than 35. Tungsten’s atomic number is 74 and atomic weight is 183. 84. 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 to do so with a half-life of (1. 8 ± 0. 2)? 018 yr; on average, this yields about two alpha decays of 180W in one gram of natural tungsten per year. Tungsten also has 4 meta states, the most stable being 179mW (T? 6. 4 minutes).
Bibliography
- J. J. R. Frausto da Silva and R. J. P. Williams, The Biological Chemistry of the Elements: The Inorganic Chemistry of Life, pp. 459-461,2001
- Jan Reedijk and Elisabeth Bouwman, Bioinorganic Catalysis, second edition, pp. 181-152, 1999
- Wiley VCH Verlay, Encyclopedia of the Elements, pp. 605-619, 2004
- Mark Winter, www. webelements. com/? tungsten/? isotopes. html, 1993-2010
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