Mo
Molybdenum
MOLYBDENUM
TRANSITION ELEMENT: CHROMIUM GROUP
| Atomic number: | 42 |
| Group numbers: | 6 |
| Period: | 5 |
| Electronic configuration: | [Kr] 4d5 5s1 |
| Formal oxidation number: | +6 |
| Electronegativities: | 2.16 |
| Atomic radius / pm: | 136.3 |
| Relative atomic mass: | 95.95(1) |
Molybdenum was discovered by Carl William Scheele (SE) in 1778. The origin of the name comes from the Greek word molybdos meaning lead. It is a silvery white, very hard metal, but is softer and more ductile than tungsten. Molybdenum is found in the minerals molybdenite (MoS2) and wulfenite (MoO4Pb). Its alloys are used in aircraft, missiles and protective coatings in boiler plate. The price of 99.7 % pure molybdenum pellets is 96.90 € for 500 g.
| Density / g dm-3: | 10220 | (293 K) |
| 9330 | (m.p.) | |
| Molar volume / cm3mol-1: | 9.39 | (293 K) |
| 10.28 | (m.p.) | |
| Electrical resistivity / µΩcm: | 5.34 | (20 °C) |
| Thermal conductivity / W m-1K-1: | 138 |
| Melting point / °C: | 2623 |
| Boiling point / °C: | 4639 |
| Heat of fusion / kJ mol-1: | 27.6 |
| Heat of vaporization / kJ mol-1: | 589.9 |
| Heat of atomization / kJ mol-1: | 656.55 |
| First ionization energy / kJ mol-1: | 684.32 |
| Second ionization energy / kJ mol-1: | 1559.21 |
| Third ionization energy / kJ mol-1: | 2617.67 |
| in the atmosphere / ppm: | - |
| in the Earth's crust / ppm: | 1 |
| in the oceans / ppm: | 0.01 |
| Crystal structure: | body-centered cubic |
| Unit-cell dimensions / pm: | a=314.700 |
| Space group: | Im3m |
| Isotope | Relative atomic mass | Mass percent (%) |
|---|---|---|
| 92Mo | 91.906810(4) | 14.84(4) |
| 94Mo | 93.905088(2) | 9.25(3) |
| 95Mo | 94.905841(2) | 15.92(5) |
| 96Mo | 95.904679(2) | 16.68(5) |
| 97Mo | 96.906021(2) | 9.55(3) |
| 98Mo | 97.905408(2) | 24.13(7) |
| 100Mo | 99.907477(6) | 9.63(3) |
| Balanced half-reaction | Eo / V | |
|---|---|---|
| MoVI + e- → MoV | +0.43 | (4.6 mol dm-3 H2SO4) |
| MoIII + 3e- → Mo(s) | - 0.2 | |
| H2MoO4(aq) + 2H+ + e- → MoO2+ + 2H2O | +0.4 | |
| HMoO4- + 3H+ + 2e- → MoO2 + 2H2O | +0.429 | |
| MoO42- + 4H+ + 2e- → MoO2 + 2H2O | +0.606 | |
| HMoO4- + 7H+ + 3e- → Mo3+ + 4H2O | +0.390 | |
| MoO42- + 8H+ + 3e- → Mo3+ + 4H2O | +0.508 | |
| MoO42- + 8H+ + 6e- → Mo(s) + 4H2O | +0.154 | |
| MoO42- + 4H2O + 6e- → Mo(s) + 8OH- | - 1.05 |
| 41 Niobium | ← | 42 Molybdenum | → | 43 Technetium |
Citing this page:
Generalic, Eni. "Molybdenum." EniG. Periodic Table of the Elements. KTF-Split, 13 Feb. 2025. Web. {Date of access}. <https://www.periodni.com/mo.html>.
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