Periodic Table -> Molybdenum
Molybdenum DetailsMolybdenum Symbol:
MoMolybdenum Atomic Number:
42Molybdenum Atomic Weight:
95.94What is Molybdenum?
(atomic number 42, symbol Mo) is a chemical element and a silvery metal, which readily forms stable, hard carbides. It has the 6th highest melting point of all elements and is often used in steel alloys. The element occurs in minerals in different oxidation states and is not found as a free metal in nature.
Minerals containing molybdenum have been known for a long time, but the element itself was discovered in 1778 by Carl Wilhelm Scheele. In 1781, Peter Jacob Hjelm isolated the element using linseed oil and carbon. Molybdenum had no industrial application for about a century due to the immaturity of metallurgical techniques, difficulty extracting the metal in pure form, and its relative scarcity.
In its pure form, the element has a Mohs hardness of 5.5 and is silvery-white in color. Molybdenum has a melting point of 4,753 °F (2,623 °C), and of all elements occurring in nature, only carbon, tungsten, rhenium, osmium, and tantalum have higher melting points.
The metal has 35 known isotopes ad 4 nuclear isomers. The isotopes range from 83 to 117 in atomic mass and 7 of them occur naturally. The only unstable, naturally occurring isotope of molybdenum is molybdenum-100. The unstable isotopes of this element decay into ruthenium, technetium, and niobium isotopes.
The largest global producers of molybdenum are Peru, the United States, Chile, China, and Canada. Molybdenite is the major commercial source of this metal although it is found in powellite, wulfenite, and other minerals. The metal is both recovered as a byproduct of tungsten and copper mining and extracted as a principal ore. Molybdenite is the main product of large mines in British Columbia and Colorado while it is the byproduct of copper mining in northern Chile and Utah.
Given that the element has a high melting point, it is used in the manufacturing of electrically-heated glass furnaces. It is also used in the production of some electrical filaments, aircraft and missile parts as well as in the nuclear power industry. Petroleum refining also uses the metal as a catalyst. In addition, molybdenum powders are used in the production of circuit inks.
One of the main applications of molybdenum is as an alloying agent for steel. Molybdenum is added in concentrations up to 8 percent to form high-strength alloys. Molybdenum also forms corrosion and heat resistant materials when alloyed with nickel, and these have application in the chemical industry. One of the element’s compounds, molybdenum disulphide is used as a high-temperature lubricant. Another compound of molybdenum, molybdenum trioxide helps adhere enamels to metals. There are other compounds of molybdenum as well, including molybdenum phosphide, molybdenum hexafluoride, and molybdic acid.
Different animal experiments have shown that the element and its compounds are very toxic. Workers who were chronically exposed to molybdenum in a Soviet Mo-Cu plant had liver dysfunction with hyperbilirubinemia. Inhabitants and factory workers in some molybdenum-rich regions of Armenia had signs of gout, with the main symptoms being erythema, articular deformities, joint pain in the feet, hands, and knees, and edema of the joint areas. While the element is vital for all species, it is very toxic in larger amounts. In comparison to other micronutrients in the soil, molybdenum is more soluble in alkaline soils and less soluble in acidic ones. As a result, its availability to plant species depends on drainage conditions and pH.
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