Platinum
transition metalProperties
| Property | Value |
|---|---|
| Atomic Mass | 195.08 amu |
| Category | transition metal |
| Group | 10 |
| Period | 6 |
| Electron Configuration | [Xe] 4f14 5d9 6s1 |
| Electronegativity | 2.28 (Pauling) |
| Oxidation States | 4, 2 |
| Melting Point | 2041.4 K (1768.3 °C) |
| Boiling Point | 4098 K (3824.8 °C) |
| Density | 21.45 g/cm³ |
| Discovered By | Antonio de Ulloa (1735) |
About Platinum
Platinum is the metal chemists reach for when nothing else will hold up. Concentrated acids slide off it, oxygen at 1500 °C does almost nothing to it, and its 5d⁹ 6s¹ valence makes it one of the best heterogeneous catalyst surfaces ever characterized. That's why a platinum gauze sits at the heart of the Ostwald process oxidizing ammonia to nitric oxide, why Pt nanoparticles on alumina catalyze CO and hydrocarbon oxidation in three-way converters, and why Pt-on-carbon is the standard cathode in PEM fuel cells dissociating O₂. The platinum-loop crucible is still how you assay refractory oxides at 1700 °C without contaminating the melt. Spanish miners in the 17th-century Chocó region named it platina del Pinto — the little silver of the Pinto river — when they pulled it from gold gravels and couldn't melt it. The most consequential platinum compound is cisplatin, cis-[Pt(NH₃)₂Cl₂], which Barnett Rosenberg stumbled into in 1965 while electrolyzing bacteria with what he thought were inert Pt electrodes; the square-planar Pt(II) center crosslinks DNA at adjacent guanines and now cures over 90% of testicular cancers.
Fun Fact
The chemotherapy drug cisplatin, discovered by accident in 1965 when a researcher noticed that platinum electrodes inhibited bacterial growth, has cured over 90 percent of testicular cancer patients and saved millions of lives.
Common Uses
- PEM fuel-cell cathode catalyst for the oxygen reduction reaction
- Ostwald-process gauze catalyst converting NH₃ to NO en route to nitric acid
- Three-way catalytic converters paired with palladium and rhodium
- Cisplatin, carboplatin, and oxaliplatin as front-line DNA-crosslinking chemotherapeutics
- Pt/Rh thermocouples and laboratory crucibles for refractory oxide melts