تنجستن (W)

الاكتشاف والتاريخ

تاريخ الاكتشاف: 1783 · Juan José Elhuyar

In 1781, Carl Wilhelm Scheele discovered that a new acid, tungstic acid, could be made from scheelite (at the time called tungsten). Scheele and Torbern Bergman suggested that it might be possible to obtain a new metal by reducing this acid. In 1783, José and Fausto Elhuyar found an acid made from wolframite that was identical to tungstic acid. Later that year, at the Royal Basque Society in the town of Bergara, Spain, the brothers succeeded in isolating tungsten by reduction of this acid with charcoal, and they are credited with the discovery of the element (they called it "wolfram" or "volfram"). The strategic value of tungsten came to notice in the early 20th century. British authorities acted in 1912 to free the Carrock mine from the German owned Cumbrian Mining Company and, during World War I, restrict German access elsewhere. In World War II, tungsten played a more significant role

الاستخدامات والتطبيقات

أنتج حوالي 61,300 طن من مركزات التنغستن في عام 2009. يستخرج خامات التنغستن، على عدة مراحل. يتم تحويل المعدن الخام في نهاية المطاف إلى أكسيد tungsten(VI) (WO3)، التي يتم تسخينها مع الهيدروجين أو الكربون لإنتاج مسحوق التنغستن. ويبلغ ثمن المعدن النقي يبلغ حوالي 20,075 دولار الطن اعتبارا من تشرين الأول/أكتوبر 2008.

النظائر

Naturally occurring tungsten consists of four stable isotopes (182W, 183W, 184W, and 186W) and one very long-lived radioisotope, 180W. 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)×1018 years; on average, this yields about two alpha decays of 180W per gram of natural tungsten per year. Another 34 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. All of the remaining radioactive isotopes have half-lives of less than 3 hours, and most of these have half-lives below 8 minutes. Tungsten also has 12 meta states, with the most stable being 179mW (t½ 6.4 minut