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78Pt195.08

Element 78, a transition metal

Platinum

A precious metal rarer than gold, the catalyst that cleans diesel exhaust, and the core of a widely used cancer drug.

At a glance

Symbol
Pt
Atomic number
78
Average atomic mass
195.08
Group
10
Period
6
Family
transition metal
Electron configuration
[Xe] 4f¹⁴ 5d⁹ 6s¹
Electronegativity
2.28
Common ions
+2 and +4

On the table

Periodic table with Platinum highlighted123456789101112131415161718123456757-7189-103HHeLiBeBCNOFNeNaMgAlSiPSClArKCaScTiVCrMnFeCoNiCuZnGaGeAsSeBrKrRbSrYZrNbMoTcRuRhPdAgCdInSnSbTeIXeCsBaLaCePrNdPmSmEuGdTbDyHoErTmYbLuHfTaWReOsIrPtAuHgTlPbBiPoAtRnFrRaAcThPaUNpPuAmCmBkCfEsFmMdNoLrRfDbSgBhHsMtDsRgCnNhFlMcLvTsOg

Period 6, group 10. The other transition metals are tinted, and every cell opens its own article.

Electrons and bonding

Like other transition metals, platinum loses its outer s electrons, and often some d electrons as well, to form positive ions, and it can form more than one kind.

Properties

State at 25 °C
solid
What it looks like
dense, silvery-white metal that never tarnishes
Melting point
1768.4 °C
Boiling point
3825 °C
Density
21.5 g/cm³

Where it is found

Found as native grains and in nickel-copper ores. South Africa's Bushveld Complex supplies about 70% of the world's platinum, with Russia next.

Discovery and name

Peoples of pre-Columbian South America worked it into jewelry. Spanish colonists dismissed it as platina, little silver, an annoying impurity in gold, and Antonio de Ulloa described it scientifically in 1748. Its name comes from that Spanish word.

What it is used for

Catalytic converters, especially for diesel vehicles, take the largest share, followed by jewelry and investment bars. Platinum catalysts make nitric acid and refine gasoline, platinum electrodes serve in fuel cells and labs, and cisplatin, a platinum compound, has treated testicular, ovarian and other cancers since the 1970s.

In compounds

Pt(NH₃)₂Cl₂cisplatin, a cancer drugPtO₂platinum dioxide, a catalystH₂PtCl₆hexachloroplatinic acidPtCl₂platinum(II) chloride