Molybdenum (Mo)
Molybdenum (Mo) is element 42, a transition metal. Atomic mass 95.95, configuration [Kr] 4d⁵ 5s¹. Properties, isotopes, oxidation states, uses and history, with an interactive 3D atom model.
Key facts
| Atomic number | 42 |
|---|---|
| Symbol | Mo |
| Standard atomic weight | 95.95(1) |
| Category | Transition Metal |
| Group | 6 |
| Period | 5 |
| State at room temperature | Solid |
| Electron configuration | [Kr] 4d⁵ 5s¹ |
| Valence electrons | 1 (Variable) |
| Common oxidation states | +4, +6 |
| Common ions | No common ions |
| Electronegativity (Pauling) | 2.16 |
| First ionization energy | 684 kJ/mol |
| Electron affinity | 72.17 kJ/mol |
| Atomic radius | 190 pm |
| Density | 10.2 g/cm³ |
| Melting point | 2622°C |
| Boiling point | 4639°C |
| Specific heat | 0.251 J/(g·°C) |
Natural isotopes
- Mo-92: Stable
- Mo-94: Stable
- Mo-95: Stable
- Mo-96: Stable
- Mo-97: Stable
- Mo-98: Stable
- Mo-100: Stable
Common uses
- High-strength steel alloys
- Lubricants (MoS₂)
- Nuclear imaging (Mo-99 precursor)
Where it matters
- Enzymatic function (Essential for nitrogen fixation in plants)
Hazards
- Toxic in high doses
- essential trace element
History
| Discovered | 1778 |
|---|---|
| Discovered by | Carl Wilhelm Scheele |
| Name | From Greek molybdos (lead-like) |