molybdenum
Heavy, hard, lustrous, silver-white, metallic element, atomic number 42, relative atomic mass 95.94. The chief ore is the mineral molybdenite (MoS2). The element is highly resistant to heat and conducts electricity easily. It is used in alloys, often to harden steels. It is a necessary trace element in human nutrition, and it is also important for nitrogen fixation. It was named in 1781 by Swedish chemist Karl Scheele, after its isolation by another Swedish chemist Peter Jacob Hjelm (1746–1813), for its resemblance to lead ore.
It has a melting point of 2,620°C, and is not found in the free state. As an aid to lubrication, molybdenum disulphide (MoS2) greatly reduces surface friction between ferrous metals and plays a role in important industrial processes. Producing countries include Canada, the USA, and Norway.
| German chemists 1995 built the largest ever wheel-shaped molecule made up of 154 molybdenum atoms surrounded by oxygen atoms. It has a relative molecular mass of 24,000 and is soluble in water. |
