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74. TungstenName: Tungsten
Pure tungsten is a steel-gray to tin-white metal. Tungsten has the highest melting point and lowest vapour pressure of all metals, and at temperatures over 1650°C has the highest tensile strength. The metal oxidises in air and must be protected at elevated temperatures. It has excellent corrosion resistance and is attacked only slightly by most mineral acids. Enzymes called oxidoreductases use tungsten in a way that is similar to molybdenum by using it in a tungsten-pterin complex. On August 20, 2002 officials representing the U.S.-based Centers for Disease Control and Prevention announced that urine tests on leukemia patient families and control group families in the Fallon, Nevada area had shown elevated levels of the metal tungsten in the bodies of both groups. 16 recent cases of cancer in children were discovered in the Fallon area which has now been identified as a "Cancer Cluster." Dr. Carol H. Rubin, a branch chief at the CDC, said data demonstrating a link between tungsten and leukemia are not available at present. Tungsten (Swedish tung sten meaning "heavy stone", even though the current name for the element in Swedish is Wolfram) was first hypothesized to exist by Peter Woulfe in 1779 who examined wolframite and concluded that it must contain a new substance. In 1781 Carl Wilhelm Scheele ascertained that a new acid could be made from tungstenite. Scheele and Torbern Bergman suggested that it could be possible to obtain a new metal by reducing tungstic acid. In 1783 Jose and Fausto Elhuyar found an acid in wolframite that was identical to tungstic acid. In Spain later that year the brothers succeeded in isolating tungsten through reduction of this acid with charcoal. They are credited with the discovery of the element. Quick links
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