Molybdenum
transition metalProperties
| Property | Value |
|---|---|
| Atomic Mass | 95.95 amu |
| Category | transition metal |
| Group | 6 |
| Period | 5 |
| Electron Configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 4d5 |
| Electronegativity | 2.16 (Pauling) |
| Oxidation States | 6, 5, 4, 3, 2 |
| Melting Point | 2896 K (2622.8 °C) |
| Boiling Point | 4912 K (4638.9 °C) |
| Density | 10.28 g/cm³ |
| Discovered By | Carl Wilhelm Scheele (1778) |
About Molybdenum
Molybdenum is one of those elements that sneaks into everything once you start looking. Its 2,896 K melting point sits sixth on the periodic table, which is why a few percent in stainless steel buys you the creep resistance that lets a turbine blade survive at 700 °C. The half-filled 4d⁵5s¹ configuration gives it the full +2 through +6 oxidation state ladder, and Mo(VI) shows up everywhere — as MoO₃ in catalyst beds, as the molybdate anion MoO₄²⁻ in aqueous chemistry, and as the active site in nitrogenase, where the FeMo cofactor breaks the N≡N triple bond at ambient temperature (a feat the Haber-Bosch process needs 400 °C and 200 atm to match). Scheele identified the element in 1778 from molybdenite, MoS₂, which is still both the main ore and a useful dry lubricant in its own right because the layered S-Mo-S sheets shear past each other almost frictionlessly. The bulk of world supply is a byproduct of porphyry copper mining.
Fun Fact
Molybdenum is the active site in nitrogenase — the enzyme certain bacteria use to break N≡N at ambient temperature and pressure. Haber-Bosch needs 200 atm and 400 °C to do the same chemistry, which is why nitrogenase has been an unsolved bioinorganic puzzle for sixty years.
Common Uses
- Strengthening alloy in 316 stainless and HSLA structural steels
- Co-Mo and Ni-Mo hydrodesulfurization catalysts in oil refining
- MoSi₂ heating elements for furnaces above 1,800 °C
- MoS₂ dry-film lubricant for vacuum and high-load bearings
- Trace nutrient in fertilizers for legumes and brassicas