molibdenum

Molybdenum is a chemical element with the symbol Mo and atomic number 42. It is a transition metal known for its high strength, high melting point, and notable corrosion resistance. Its density is about 10.28 g/cm3, and it melts at approximately 2,623°C and boils at about 4,639°C. In pure form it is a silvery‑white metal that remains stable at high temperatures.

Molybdenum occurs primarily in the mineral molybdenite (MoS2), which is the major source for its extraction. It is also found in various other minerals and as a trace constituent in some rocks. Global production concentrates in several countries, with large outputs from China, the United States, Chile, and Peru. The metal is obtained through roasting and reduction processes and is then refined into pure molybdenum metal or further converted into alloys and compounds.

The principal uses of molybdenum are in metallurgy and catalysis. It is added to steel and other alloys to improve strength, toughness, and high‑temperature performance, making it common in stainless steels and high‑strength low‑alloy steels. Molybdenum compounds, particularly molybdenum disulfide (MoS2), serve as solid lubricants. In the chemical industry, molybdenum‑based catalysts are employed in hydrodesulfurization and other refinery processes to remove sulfur and other contaminants from petroleum products.

Biologically, molybdenum is an essential trace element for many organisms, including humans, where it is part of several enzymes such as xanthine oxidase and sulfite oxidase. It is obtained in the diet from foods like legumes, grains, and leafy vegetables. Exposure to high levels of certain molybdenum compounds can be harmful, but at normal dietary levels the element is considered safe and necessary for biological function. The name derives from the Greek molybdos, meaning lead, reflecting early similarities to lead ores, and the element was isolated in the late 18th century.