Molybdenum (from the Greek meaning "lead-like"), is a Group 6 chemical element with the symbol Mo and atomic number 42. It has the sixth-highest melting point of any element, and for this reason it is often used in high-strength steel alloys. Molybdenum is found in trace amounts in plants and animals, although excess molybdenum can be toxic in some animals. Molybdenum was discovered in 1778 by Carl Wilhelm Scheele and first isolated in 1781 by Peter Jacob Hjelm.
| Technical Data | ||||||||
| Symbol | Mo | Melting point /°C | 1620 | |||||
| Atomic number | 42 | Boiling point /°C | 4650 | |||||
| No. of naturally occurring isotopes | 7 | ΔHfus/kJmol-1 | 28(+/-3) | |||||
| Atomic weight | 95.94 | ΔHvap/kJmol-1 | 590(+/-21) | |||||
| Electronic configuration | [Kr]4d5s7 | ΔHf(monoatomic gas)/kJmol-1 | 664(+/-13) | |||||
| Metal radius( 12-coordinate)/pm | 139 | Electrical resistivity (20°C)/μohm cm | ~5 | |||||
| Ionic radius(6-coordinate)/pm VI | 59 | Electronegativity χ | 1.8 | |||||
| Ionic radius(6-coordinate)/pm V | 61 | Ionization energy/kJmol-1 I | 685 | |||||
| Ionic radius(6-coordinate)/pm IV | 65 | Ionization energy/kJmol-1 II | 1558 | |||||
| Ionic radius(6-coordinate)/pm III | 69 | Ionization energy/kJmol-1 III | 2621 | |||||
| Density (20°C)/gcm-3 | 10.28 | |||||||
| Evaporation Techniques | ||||||||
| Temperature (oC) @Vap. Pressure | Techniques | Remarks | ||||||
| 10-8 Torr | 10-6 Torr | 10-4 Torr | Electron Beam | Crucible | Coil | Boat | ||
| 1592 | 1822 | 2117 | Excellent | - | - | - | Films smooth, hard. Careful degas required. Go to Evaporation Sources Page | |