The first significant practical use of this metal (discovered in 1778 by Scheele) was in the alloy used to manufacture the German artillery gun known to the Allies as Big Bertha. The metal takes its name from the Greek word molybdos, meaning "lead" because some of its compounds were once confused with similar lead compounds before Scheele's discovery. The pure metal was first isolated in 1781 by Peter Jacob Hjelm.
Chemically, molybdenum resembles a cross between Cr and W. It has a principal oxidation state of +6 although ionic compounds suggest lower states (e.g., the common ore is \(MoS_2\)).
Molybdenum contributes to the toughness and hardenability of quenched and tempered steels. It is also an essential plant nutrient. Some lands are actually barren for lack of this element in the soil.
Stephen R. Marsden (ChemTopics)