Molybdenum By: Mikaela DeBari & Austin King
Chemical Properties • Atomic number: 42 • Atomic mass: 95.94g.mol-1 • Electro negativity: 1.8 • Density: 10.2g.cm-3 at 20 degrees C • Melting point: 2610 degrees C • Boiling point: 4825 degrees C • Vanderwaals radius: 0.139 nm • Ionic radius: 0.068nm(+4) ; 0.06(+6) • Isotopes: 11 • Electronic Shell: [ Kr ] 4d^5 5s^1 • Energy of first ionization: 651 kJ.mol^-2 • Discovered by Carl Wilhelm Scheele in 1778
Physical Properties • This metal is a silvery white, very hard transition metal. • It was often confused with graphite and lead ore • Its melting point is higher than most pure elements, besides tungsten and tantalum • Oxidizes at elevated temperatures .
Application • Molybdenum is used as an alloy agent and is valuable because it contributes to the toughness of quenched and tempered steels. • It can also be used to improve the strength of steel at higher temperatures. • It is used in nickel-based alloys, such as the “Hastelloys(R)” which are heat resistent and corrosion resistant to chemical solutions • There is a recent application for molybdenum as electrodes for electrically heated glass furnaces and foreheaths. • Used in nuclear energy applications and for missile and aircraft parts. • Can also be used as a lubricant at high heats where oils would decompose.
Environmental Use • Molybdenum is less soluble in acidic soils and more soluble in alkaline soils, so it is more available for plants with sensativity to pH and drainage conditions. • Environmental Effects: • Molybdenum is essential to all species, but is only essential in small amounts, in large amounts it is highly toxic. • Too much molybdenum can cause fetal deformities
Health effects • Molybdenum is a highly toxic metal. • Liver dysfunction with hyperbilirubinemia was reported in workmen who were exposed to Mo-Cu plant. • Has caused gout in factory workers and in Mo- rich areas of Armenia.