Molybdenum is a silvery white metalelement denoted by the atomic symbol, Mo. Its atomic number is 42 and it has an atomic weight of 95.94. It melts at a higher temperature than all but two other readily available metals ( tungsten and tantalum); its melting point, 4753.443° F (2623° C), is the sixth highest of all the elements. Most molybdenum comes from an ore called molybdenite, which is a compound of molybdenum and sulfur (MoS₂).

Before the 1770s, scientists confused molybdenite with other substances such as lead ore and graphite. Then in 1778, Carl Scheele recognized that molybdenite was a distinct ore of a new element. However, molybdenum was not isolated until 1782, when Swedish mineralogist Peter Jacob Hjelm (1746-1813) prepared the silvery-white metal in an impure form. Hjelm was a friend of Scheele's, and it was Scheele's suggestions that led Hjelm to isolate not only molybdenum, but also manganese.

In addition to...