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Platinum (Pt)
Platinum (symbol Pt) is the chemical element with atomic number 78: a transition metal, solid at 0 °C, with an atomic mass of 195.08 u. Discovered in 1735 (Antonio de Ulloa).
Platinum is a dense, untarnishable precious metal, rarer than gold. Its main talent is catalysis: it speeds up chemical reactions without being used up, which puts it at the heart of catalytic converters. One of its compounds, cisplatin, is among the most widely used cancer drugs in the world.
Key facts
- Atomic number
- 78
- Symbol
- Pt
- French name
- Platine
- Atomic mass
- 195.08 u
- Molar mass
- 195.08 g/mol
- Family
- Transition metals
- Position
- period 6, group 10, d-block
- State at 0 °C
- Solid
- Melting point
- 1,768.3 °C
- Boiling point
- 3,824.9 °C
- Density
- 21.45 g/cm³
- Electronegativity (Pauling)
- 2.28
- First ionization energy
- 864 kJ/mol
- Atomic radius
- 135 pm
- Electron configuration
- [Xe] 4f¹⁴ 5d⁹ 6s¹
- Abundance in Earth's crust
- 0.005 ppm (74th most abundant element)
- Indicative price
- 28,000 $/kg (order of magnitude)
- Radioactive
- no
- Discovery
- 1735, Antonio de Ulloa
Origin of the name
From the Spanish platina, “little silver.”
What does platinum look like?
A shiny white-gray metal, very dense (21.45 g/cm³), malleable and ductile, that never tarnishes.
Where is platinum found?
About 5 parts per billion of Earth's crust. More than 70% of known reserves lie in South Africa's Bushveld Complex. It occurs in native form or in minerals such as sperrylite.
Natural sources
- Native platinum
- Sperrylite
- Cooperite
- Braggite
How is platinum produced?
About 10 tonnes of ore must be mined and processed to get one ounce (31 g) of platinum. The concentrate is smelted, then the platinum-group metals are separated chemically. Recycling of catalytic converters supplies a growing share.
Top producers
- South Africa
- Russia
- Zimbabwe
- Canada
What is platinum used for?
- Catalytic converters, with palladium and rhodium.
- Jewelry and watchmaking.
- Cancer drugs (cisplatin, carboplatin).
- Fuel cells and electrolyzers.
- Pacemaker electrodes, sensors and thermocouples.
In everyday life
- A car's catalytic converter
- A platinum wedding ring
- An engine's oxygen (lambda) sensor
- A spark plug
Role in living things
No biological role. Cisplatin kills cancer cells by binding to their DNA and preventing them from dividing.
Hazards of platinum
The metal is inert, but some platinum salts cause severe respiratory allergies in refinery workers (platinosis). Platinum-based chemotherapies have significant side effects.
Cosmic origin
- Neutron stars: Created when two neutron stars collide — the “forge” of gold.
History of platinum
Pre-Columbian peoples of present-day Ecuador were already working platinum. The conquistadors considered it a nuisance because it mixed with alluvial gold; they called it platina, “little silver.” Antonio de Ulloa described it in 1748, and it was studied in Europe in the 18th century.
Did you know?
- Cisplatin was discovered by chance in 1965: Barnett Rosenberg noticed that platinum electrodes stopped bacteria from dividing.
- The “Big K,” a platinum-iridium cylinder, defined the kilogram from 1889 to 2019.
- Spanish authorities are said to have once had platinum dumped into rivers to stop it being used to counterfeit gold.
Isotopes of platinum
Natural platinum has five stable isotopes and a trace of weakly radioactive platinum-190. Isotopes 194, 195 and 196 make up most of the metal.
- platinum-190: 0.012% of natural platinum, radioactive, half-life 4.83 × 10¹¹ years
- platinum-192: 0.782% of natural platinum, stable
- platinum-193: radioactive, half-life 50 years
- platinum-194: 32.864% of natural platinum, stable
- platinum-195: 33.775% of natural platinum, stable
- platinum-195m: radioactive, half-life 4.01 days
- platinum-196: 25.211% of natural platinum, stable
- platinum-197: radioactive, half-life 19.9 h
- platinum-198: 7.356% of natural platinum, stable
Related elements
Same family (transition metals): Scandium (Sc), Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn), Yttrium (Y), Zirconium (Zr), Niobium (Nb), Molybdenum (Mo), Technetium (Tc), Ruthenium (Ru), Rhodium (Rh), Palladium (Pd), Silver (Ag), Cadmium (Cd), Hafnium (Hf), Tantalum (Ta), Tungsten (W), Rhenium (Re), Osmium (Os), Iridium (Ir), Gold (Au), Mercury (Hg), Rutherfordium (Rf), Dubnium (Db), Seaborgium (Sg), Bohrium (Bh), Hassium (Hs).
Same column (group 10): Nickel (Ni), Palladium (Pd), Darmstadtium (Ds).