Platinum (Pt)
Platinum (Pt) is a transition metal with atomic number 78 and a standard atomic weight of 195.08. At room temperature it is a solid that melts at 1,768 °C and boils at 3,825 °C.
Platinum key facts
Platinum at a glance
Identity
| Symbol | Pt |
|---|---|
| Atomic number (Z) | 78 |
| Atomic weight | 195.08 ± 0.02 (CIAAW 2024) |
| Category | Transition metal |
| Group | 10 |
| Period | 6 |
| Block | d-block |
| CAS number | 7440-06-4 |
Atomic properties
| Electron configuration | [Xe] 4f14 5d9 6s1 Full: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d9 6s1 |
|---|---|
| Electrons per shell | 2, 8, 18, 32, 17, 1 |
| Oxidation states | +2, +4 Less common: -3, -2, -1, 0, +1, +3, +5, +6 |
| Electronegativity (Pauling) | 2.28 |
| First ionisation energy | 8.959 eV (864.4 kJ/mol) 2nd: 18.56 eV · 3rd: 29 eV |
| Electron affinity | 2.128 eV |
| Atomic radius (empirical) | 135 pm |
| Covalent radius | 123 pm |
| Van der Waals radius | 213 pm |
Physical properties
| State at 25 °C | Solid |
|---|---|
| Melting point | 1,768.2 °C · 3,214.8 °F · 2,041.35 K |
| Boiling point | 3,825 °C · 6,917 °F · 4,098.15 K |
| Density | 21.5 g/cm³ |
| Specific heat capacity | 0.133 J/(g·K) |
| Thermal conductivity | 71.6 W/(m·K) |
| Crystal structure | Face-centred cubic |
Isotopes & abundance
| Natural occurrence | Primordial |
|---|---|
| Radioactive | No |
| Natural isotopes (abundance) | 195Pt 33.775%, 194Pt 32.864%, 196Pt 25.211%, 198Pt 7.356%, 192Pt 0.782%, 190Pt 0.012% (radioactive) |
| Stable isotopes | 5 |
| Known isotopes | 44 |
| Abundance in Earth's crust | 0.005 mg/kg |
Atomic weights: CIAAW Abridged Standard Atomic Weights 2024. Other properties: standard reference compilations, checked October 2026; predicted values are marked.
Platinum electron configuration
Platinum has 78 electrons. Written in short form, its ground-state configuration is [Xe] 4f14 5d9 6s1 — the electrons of the noble gas xenon, plus 4f14 5d9 6s1.Written out in full: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d9 6s1.
An exception to the filling rule. The simple aufbau (Madelung) order predicts 6s2, 5d8, but platinum actually has 6s1, 5d9. Half-filled and filled subshells, and the close energies of the outer orbitals, make this arrangement more stable.
Discovery and name
1748 — Antonio de Ulloa (described 1748); known to pre-Columbian South Americans · Spain / Colombia.
Spanish platina, little silver.
Known for
A precious metal used in catalytic converters, jewellery, laboratory equipment and anticancer drugs such as cisplatin.
Isotopes of platinum
Naturally occurring platinum is a mix of 6 isotopes. Each has 78 protons; they differ in the number of neutrons:
| Isotope | Protons | Neutrons | Natural abundance | Stability |
|---|---|---|---|---|
| 195Pt | 78 | 117 | 33.775% | stable |
| 194Pt | 78 | 116 | 32.864% | stable |
| 196Pt | 78 | 118 | 25.211% | stable |
| 198Pt | 78 | 120 | 7.356% | stable |
| 192Pt | 78 | 114 | 0.782% | stable |
| 190Pt | 78 | 112 | 0.012% | radioactive · half-life 483 billion years |
44 isotopes of platinum are known in our data set (half-lives as published in nuclear data tables).
Platinum compared with group 10
The other elements in group 10, from top to bottom of the table:
| Element | Z | Atomic weight | Melting point | Boiling point | Density | Electronegativity |
|---|---|---|---|---|---|---|
| Nickel | 28 | 58.693 | 1,455 °C | 2,913 °C | 8.9 g/cm³ | 1.91 |
| Palladium | 46 | 106.42 | 1,555 °C | 2,963 °C | 12 g/cm³ | 2.2 |
| Platinum | 78 | 195.08 | 1,768 °C | 3,825 °C | 21.5 g/cm³ | 2.28 |
| Darmstadtium | 110 | [281] | — | — | 34.8 g/cm³ (pred.) | — |