42MoMolybdenum95.95 u
Molybdenum (Mo)
Molybdenum is a transition metal with atomic number 42, in period 5 and group 6 of the periodic table. Its atomic mass is 95.95 u and its electron configuration is [Kr] 4d⁵ 5s¹. Solid at 25 °C.
Key facts
| Atomic number | 42 |
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| Atomic mass | 95.95 u |
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| Category | Transition Metal |
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| Period | 5 |
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| Group | 6 |
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| Block | d |
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| Electron configuration | [Kr] 4d⁵ 5s¹ |
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| Electrons per shell | 2, 8, 18, 13, 1 |
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| Electronegativity (Pauling) | 2.16 |
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| Oxidation states | −4, −2, −1, +1, +2, +3, +4, +5, +6common in bold |
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| State at 25 °C | Solid |
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| Melting point | 2896 K2622.85 °C |
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| Boiling point | 4912 K4638.85 °C |
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| Density | 10.28 g/cm³ |
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Atomic properties
| First ionization energy | 7.092 eV |
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| Electron affinity | 71.9 kJ/mol |
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| Atomic radius | 139 pm |
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| Covalent radius | 154 pm |
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| Van der Waals radius | 209 pm |
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| Common ions | Mo⁶⁺ |
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| Protons, neutrons, electrons | 42, 54, 42 |
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Physical and thermal properties
| Molar volume | 9.38 cm³/mol |
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| Heat of fusion | 36 kJ/mol |
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| Heat of vaporization | 600 kJ/mol |
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| Specific heat | 251 J/(kg·K) |
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| Thermal conductivity | 139 W/(m·K) |
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| Thermal expansion | 4.8 × 10⁻⁶ K⁻¹ |
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| Mohs hardness | 5.5 |
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| Young’s modulus | 329 GPa |
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| Crystal structure | Body-centered cubic |
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| Magnetic type | Paramagnetic |
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Identification and history
| CAS number | 7439-98-7 |
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| Latin name | Molybdaenum |
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| Discovered by | Carl Wilhelm Scheele · 1778 |
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| Named by | --- |
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Natural isotopes
| Isotope | Mass (u) | Abundance |
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| 92Mo | 91.906807 | 14.649 % |
| 94Mo | 93.905084 | 9.187 % |
| 95Mo | 94.905837 | 15.873 % |
| 96Mo | 95.904675 | 16.673 % |
| 97Mo | 96.906017 | 9.582 % |
| 98Mo | 97.905404 | 24.292 % |
| 100Mo | 99.907468 | 9.744 % |
Data checked against PubChem (NIH), IUPAC, the NIST Atomic Spectra Database and the IAEA (NUBASE and AME), the same data you see in the app.
A dash (---) means there is no reliable published measurement. The app never makes one up.
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Periodic Table