Platinum
Platinum is a precious transition metal valued for corrosion resistance and catalytic activity.
Platinum makes a durable ornament and an effective catalyst.
Explore Platinum's atom- Atomic number
- 78
- Standard atomic weight
- 195.084(9)
- Family
- Transition metal
- Period
- 6
- Group
- 10
- Standard state
- Solid
In everyday life
Platinum appears in jewellery, catalytic converters and some fuel-cell catalysts.
Something to remember
Platinum is a member of the platinum-group metals alongside palladium and rhodium.
Meet its electrons
[Xe] 6s1 4f14 5d9
Published neutral-atom ground-state configuration; excited atoms and ions can differ.
Electrons per shell: 2 · 8 · 18 · 32 · 17 · 1.
The playground shows an illustrative shell model. Real electrons are described by quantum orbitals, rather than tiny planets traveling along fixed paths.
A connection to explore
Platinum and palladium are members of the platinum-group metals with catalytic applications.
Meet Palladium (Pd)Properties and conditions
- Standard atomic weight
- 195.084(9)CIAAW 2024 standard atomic weight (dimensionless). Parentheses give uncertainty in the last quoted digits. Source flags: none.CIAAW standard atomic weights ↗ · Retrieved 2026-10-15
- Standard state
- SolidPubChem classification, including explicit predictions where stated. Reference temperature and pressure are not supplied in the table.PubChem periodic table ↗ · Retrieved 2026-10-15
- First ionisation energy
- 9 eVEnergy to remove the first electron from an isolated neutral gas-phase atom. Uncertainty is not supplied.PubChem periodic table ↗ · Retrieved 2026-10-15
- Electronegativity
- 2.28 Pauling scaleA dimensionless relative measure; values depend on the chosen scale. Uncertainty is not supplied.PubChem periodic table ↗ · Retrieved 2026-10-15
- Melting point
- 2041.55 KPubChem reported value. Pressure, allotrope and measurement uncertainty are not specified in the table; consult the cited source.PubChem periodic table ↗ · Retrieved 2026-10-15
- Boiling point
- 4098 KPubChem reported value. Pressure and measurement uncertainty are not specified in the table; consult the cited source.PubChem periodic table ↗ · Retrieved 2026-10-15
- Density
- 21.46 g/cm³PubChem reported value. Temperature, pressure, allotrope and measurement uncertainty are not specified in the table; gas densities are especially condition-dependent.PubChem periodic table ↗ · Retrieved 2026-10-15
- Oxidation states
- +4, +2Selected PubChem oxidation states; formal electron bookkeeping, not a list of stable free-ion charges or every possible compound.PubChem periodic table ↗ · Retrieved 2026-10-15
- Discovery
- 1735PubChem discovery attribution. Ancient knowledge and competing priority claims cannot always be represented by a single year.PubChem periodic table ↗ · Retrieved 2026-10-15
- Atomic radius
- 209 pmPubChem tabulated radius. Radius definitions depend on bonding and convention; measurement definition and uncertainty are not supplied in this table.PubChem periodic table ↗ · Retrieved 2026-10-15
- Electron affinity
- 2.128 eVPubChem reported gas-phase electron affinity. Sign conventions and electronic states matter; uncertainty is not supplied in this table.PubChem periodic table ↗ · Retrieved 2026-10-15
Isotopes, abundance and decay
Isotopes share a proton count but have different neutron counts. This selection includes naturally tabulated compositions and a reference isotope for other elements. It is not a list of every known isotope.
Explore 6 isotopes of Pt
| Isotope | Relative atomic mass | Natural fraction | Half-life | Decay |
|---|---|---|---|---|
| Pt-190 | 189.9599297(63) | 0.00012(2) | 483 Gy (uncertainty 3) | ;α=100;2β+ ? |
| Pt-192 | 191.9610387(32) | 0.00782(24) | No decay observed | ;A ? |
| Pt-194 | 193.9626809(10) | 0.3286(40) | No decay observed | No decay tabulated |
| Pt-195 | 194.9647917(10) | 0.3378(24) | No decay observed | ;A ? |
| Pt-196 | 195.96495209(99) | 0.2521(34) | No decay observed | No decay tabulated |
| Pt-198 | 197.9678949(23) | 0.07356(130) | No decay observed | ;2β− ?;A ? |
Fractions use NIST’s terrestrial isotopic compositions, which can vary by sample. Parentheses denote uncertainty in the last digits. Half-lives and decay branches use NUBASE2020; # marks estimates, >/< mark limits. “No decay observed” follows that evaluation and does not prove permanent stability. Decay branch intensities are percentages; SF means spontaneous fission, EC electron capture, IT an isomeric transition.
Follow the science
Use these original references to explore the data and context. Atomic weights can vary with isotope composition; values for elements without stable isotopes may describe a representative isotope rather than a standard atomic weight.