|
( Molybdenum)
Molybdenum (pronounced /m?'l?bd?n?m/, from the Greek word for the metal "lead"), is a Group 6 chemical element with the symbol Mo and atomic number 42. It has the eighth-highest melting point of any element, and for this reason it is often used in high-strength steel alloys. Molybdenum is found in trace amounts in plants and animals, although excess molybdenum can be toxic in some animals. Molybdenum was discovered in 1778 by Carl Wilhelm Scheele and first isolated in 1781 by Peter Jacob Hjelm. Molybdenum is a transition metal with an electronegativity of 1.8 on the Pauling scale and an atomic mass of 95.9&_160;g/mole.[2] It does not react with oxygen or water at room temperature. At elevated temperatures, molybdenum trioxide is formed in the reaction 2Mo + 3O2 ? 2MoO3.[3] In its pure metal form, molybdenum is silvery white with a Mohs hardness of 5.5, though it is somewhat more ductile than tungsten. It has a melting point of 2623°C, and, of the metals, only tantalum, osmium, rhenium, and tungsten have higher melting points.[4] Molybdenum burns only at temperatures above 600°C.[5] It also has the lowest heating expansion of any commercially used metal.[6] Molybdenum has a value of approximately $65,000 per tonne as of 4 May 2007. It maintained a price at or near $10,000 per tonne from 1997 through 2002, and reached a high of $103,000 per tonne in June 2005.[7]
|
Molybdenum Subcategories
Molybdenum Articles
|
|
