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.