Platinum
[Xe] 4f¹⁴ 5d⁹ 6s¹ · 2 · 8 · 18 · 32 · 17 · 1
A noble metal the Spanish conquistadors threw away as a useless contaminant of gold. Today platinum underpins automotive catalysts, is a key industrial catalyst, and is a cancer drug.
3D model
Bohr model: nucleus and electron shells from the real configuration. Valence electrons are highlighted.
Drag to rotate, scroll to zoom
Atomic properties
- Atomic number
- 78
- Atomic mass
- 195.084 а.е.м.
- Electron configuration
- [Xe] 4f¹⁴ 5d⁹ 6s¹
- Electrons per shell
- 2 · 8 · 18 · 32 · 17 · 1
- Block
- d-block
- Group
- Nickel group
- Period
- 6
- Electronegativity (Pauling)
- 2.28
- Electronegativity (Allen)
- 1.72
- Atomic radius
- 177 pm
- Covalent radius
- 136 pm
- Van der Waals radius
- 175 pm
- Ionisation energy 1
- 870 kJ/mol
- Ionisation energy 2
- 1 791 kJ/mol
- Electron affinity
- 205.3 kJ/mol
- Common oxidation states
- +2, +4
- Oxidation states
- -3, -2, -1, +1, +2, +3, +4, +5, +6
Physical properties
- State at 25 °C
- solid
- Density
- 21.45 g/cm³
- Melting point
- 2 041.4 K · 1 768.3 °C
- Boiling point
- 4 098 K · 3 824.9 °C
- Speed of sound
- 2 680 m/s
Thermal properties
- Heat of fusion
- 22.17 kJ/mol
- Heat of vaporisation
- 469 kJ/mol
- Specific heat capacity
- 0.133 J/(g·K)
- Thermal conductivity
- 71.6 W/(m·K)
Mechanical properties
- Young's modulus
- 168 GPa
- Shear modulus
- 61 GPa
- Bulk modulus
- 230 GPa
- Poisson ratio
- 0.38
- Mohs hardness
- 3.5
- Brinell hardness
- 392 MPa
Electrical and magnetic properties
- Electrical resistivity
- 105 nΩ·m
- Magnetic ordering
- paramagnetic
- Curie point
- no data
- Néel point
- no data
- Superconducting point
- no data
Crystal structure
- Crystal structure
- face-centred cubic (fcc)
- Lattice constants
- a = 392.42 pm
Abundance
- In the crust
- 0.005 mg/kg
- In the ocean
- 0 mg/L
- In the universe
- 0.005 mg/kg
- In the human body
- 0 mg/kg
Isotopes
| Isotope | Abundance | Half-life | Decay mode |
|---|---|---|---|
| 190Pt | 0.012 % | 20 597.68 yr | α |
| 192Pt | 0.782 % | stable | — |
| 194Pt | 32.86 % | stable | — |
| 195Pt | 33.78 % | stable | — |
| 196Pt | 25.21 % | stable | — |
| 198Pt | 7.36 % | stable | — |
Platinum-190 is faintly radioactive with a 6.5·10¹¹-year half-life. Platinum-195 is used in NMR studies of how the anticancer drugs work.
Discovery
- Year of discovery
- 1735
- Discovered by
- Antonio de Ulloa
- Where
- Colombia
- Origin of the name
- from Spanish platina (little silver): the Spanish took it for spoiled silver
History
Pre-Columbian peoples of Ecuador worked platinum long before Europeans. Antonio de Ulloa described it in 1735 as platina, little silver: the Spanish took it for spoiled silver and ordered it thrown back into the river.
Where it occurs
0.005 mg/kg of the crust. Mined from platinum placers and copper-nickel sulfides; over 70 % comes from the Bushveld complex in South Africa.
How it is produced
From concentrates by a long chain separating the six platinum metals. A notable share of supply is recycled from spent catalytic converters.
Role in living things
No biological role. Cisplatin works by forming cross-links in DNA that stop a cell from dividing.
Safety
The metal is inert. Platinum salts are strong allergens causing occupational asthma. Platinum chemotherapy comes with severe side effects.
Uses
- Diesel engine catalytic converters
- Catalysts in oil refining and nitric acid production
- Cisplatin and carboplatin — drugs that cure most cases of testicular cancer
- Jewellery and bullion
- Fuel cell electrodes and laboratory ware
Curiosities
- Cisplatin was found by accident in 1965: platinum electrodes in a bacterial culture unexpectedly stopped cells dividing.
- Testicular cancer survival rose from 10 % to over 95 % after platinum drugs arrived.
- The Spanish called platinum little silver and dumped it in the river to keep it from spoiling gold.
- Platinum is dense enough that an ingot the size of a soft drink can weighs about 15 kilograms.