Platinum (Pt)
“The metal Spanish gold-washers cursed as “little silver” — today the noble catalyst that cleans every modern car’s exhaust.”
How its electrons are arranged
Computed from the aufbau principle, with known real-world exceptions applied automatically.
Characteristics
- Chemically noble: untouched by air, water and single acids at room temperature — only aqua regia and molten alkalis slowly dissolve it, so a platinum surface keeps its polish for centuries.
- A catalytic superstar — hydrogen and oxygen can recombine into water on platinum gauze at room temperature; that quiet power drives exhaust cleaning and mountains of industrial chemistry.
- Dense (21.45 g/cm³) and melting at 1,768 °C, yet so malleable in pure form that jewellers work it like gold; molten glass does not even wet its surface, a blessing for glassmakers’ stirrers.
- A known aufbau rebel: instead of the predicted [Xe] 4f¹⁴ 5d⁸ 6s², a platinum atom adopts [Xe] 4f¹⁴ 5d⁹ 6s¹, spending one 6s electron to settle into a lower-energy, near-filled 5d arrangement.
A dense, silvery-white metal with a soft, moonlit shine that never dulls. For all its nobility it is astonishingly workable — a single gram can be drawn into a fine wire hundreds of metres long, and molten glass simply refuses to stick to its surface.
Where you meet it
✦ Uses
- Catalytic converters on modern vehicles: a honeycomb washcoated with platinum (with palladium and rhodium) converts poisonous carbon monoxide and nitrogen oxides into carbon dioxide and nitrogen gas.
- Platinum crucibles and dishes in analytical chemistry — rock powders can be fused in them with caustic flux and the vessel still weighed afterwards, because nothing reacts with it.
- Cisplatin-family chemotherapy drugs, whose central platinum atom crosslinks tumour DNA — the regime that made testicular cancer largely curable.
- Prestige wedding rings and watch cases — hypoallergenic and never tarnishing — plus fine electrodes, glassmaking stirrers and the retired international prototype kilogram of platinum–iridium.
◍ Everyday examples
- A newish bus or car on Bangladeshi roads cleans its exhaust through a platinum-containing converter before the gas ever leaves the tailpipe.
- Jewellery counters in Dhaka malls stamp “PT 950” on platinum bands — 95% pure, chosen because it never blackens the skin the way some alloys do.
- Cancer wards worldwide stock cisplatin vials; the platinum atom at the drug’s heart is what jams the tumour cell’s DNA-copying machinery.
History & name
Ecuador’s pre-Columbian La Tolita smiths were sintering platinum into ornaments a thousand years before Europe knew the metal existed. Spanish colonials panning for gold cursed the stubborn white grains as platina — “little silver” — and dumped them to keep their gold pure. In 1735 the Spanish savant Antonio de Ulloa, surveying in South America, carried word of the strange metal back to Europe, where chemists wrestled for decades with a substance they could neither melt nor confidently separate from silver. Once malleable platinum was finally tamed in the early 1800s, it went on to serve as laboratory ware, the standard metre and kilogram, and the catalyst backbone of the chemical industry.