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Oxidation & Electrons | Appearance & Characteristics Reactions | Compounds | Radius | Conductivity Abundance & Isotopes 
Molybdenum. (Photo: Tomihahndorf) |
General:
| Name: Molybdenum | Symbol: Mo |
| Type: Transition Metal | Atomic weight: 95.94 |
| Density @ 293 K: 10.2 g/cm3 | Atomic volume: 9.4 cm3/mol |
| Discovered: Carl W. Scheele extracted molybdenum oxide from the mineral molybdenite (molybdena) in 1778. He concluded that the mineral contained a new element but did not isolate it. In 1781, Peter J. Hjelm isolated the metal by reducing the oxide with carbon. The element name comes from the Greek word 'molybdos', meaning lead. | |
States
| State (s, l, g): solid | |
| Melting point: 2896 K (2623 oC) | Boiling point: 4913 K (4640 oC) |
Energies
| Specific heat capacity: 0.25 J g-1 K-1 | Heat of atomization: 659 kJ mol-1 |
| Heat of fusion: 32.0 kJ mol-1 | Heat of vaporization : 598 kJ mol-1 |
| 1st ionization energy: 684.9 kJ mol-1 | 2nd ionization energy: 1588.2 kJ mol-1 |
| 3rd ionization energy: 2620.5 kJ mol-1 | Electron affinity: 72 kJ mol-1 |
Oxidation & Electrons
| Shells: 2,8,18,13,1 | Electron configuration: [Kr] 4d5 5s1 |
| Minimum oxidation number: -2 | Maximum oxidation number: 6 |
| Min. common oxidation no.: 0 | Max. common oxidation no.: 6 |
| Electronegativity (Pauling Scale): 2.16 | Polarizability volume: 12.8 Å3 |
Appearance & Characteristics
| Structure: bcc: body-centered cubic | Color: silvery-white |
| Hardness: 5.5 mohs | |
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Harmful effects: Molybdenum is toxic in all but small quantaties. Characteristics: Molybdenum is a silvery-white, high-melting metal. It does not react with oxygen or water at room temperature and it also resists corrosion at ordinary temperatures. Molybdenum oxide (MoO3) is soluble in alkaline water, forming molybdate salts. Uses: Molybdenum's strength and resistance to expanding or softening at high temperatures is particularly sought after in critical areas where high temperatures are common, such as in nuclear power plants and aircraft engines. It is also used in the petroleum industry, to catalyze the removal of organic sulfur compounds in coal liquification and gas liquification processes. Molybdenum is an essential trace element for animals and plants. As with selenium, too much of it is toxic, too little of it is fatal. In nitrogen fixing bacteria, molybenum is a vital component of the nitrogenase enzyme which allows conversion of nitrogen gas in air into nitrates vital for plant growth. Molybdenum is also present in 20 or so enzymes needed in animals' metabolisms. |
Reactions
| Reaction with air: w/ht, ⇒ MoO3 | Reaction with 6 M HCl: none |
| Reaction with 15 M HNO3: none | Reaction with 6 M NaOH: |
Compounds
| Oxide(s): MoO2, MoO3 | Chloride(s): MoCl2, MoCl3, MoCl4, MoCl5, MoCl6 |
| Hydride(s): |
Radius
| Atomic radius: 139 pm | Ionic radius (1+ ion): pm |
| Ionic radius (2+ ion): pm | Ionic radius (3+ ion): 83 pm |
| Ionic radius (2- ion): pm | Ionic radius (1- ion): pm |
Conductivity
| Thermal conductivity: 138 W m-1 K-1 | Electrical conductivity: 17.3 x 10-6 S m-1 |
Abundance & Isotopes
| Abundance earth's crust: 1.2 parts per million by weight, 0.2 parts per million by moles | |
| Abundance solar system: 9 parts per billion by weight, 0.1 part per billion by moles | |
| Cost, pure: $11 per 100g | |
| Cost, bulk: $ per 100g | |
| Source: Molybdenum is not found free in nature. The main ore of molybdenum is molybdenite, (molybdenum disulfide, MoS2). It also occurs in wulfenite (lead molybdate) and powellite (calcium molybdate). Comercially, the metal is obtained by mining molybdenite directly and it is also recovered as a by-product of copper mining. | |
| Isotopes: Molybdenum has 24 isotopes whose half-lives are known with mass numbers from 86 to 110. Of these, six are stable: 92Mo, 94Mo, 95Mo, 96Mo, 97Mo and 98Mo. The most naturally abundant is 98Mo at 24.1%. | |
