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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 - PowerPoint PPT Presentation
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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.