Platinum (Pt)
Element 78 · Transition metal · atomic mass 195.08 u · group 10, period 6
Electron shells: 2, 8, 18, 32, 17, 1
Platinum is dense, unreactive and an outstanding catalyst, which is why it sits in both catalytic converters and fuel cells. It is also the standard against which purity in jewellery is measured.
Cisplatin, a simple platinum compound, transformed testicular cancer from usually fatal to usually curable.
- Atomic number
- 78
- Atomic mass
- 195.08 u
- Electron configuration
- [Xe] 6s¹ 4f¹⁴ 5d⁹
- Group · period · block
- 10 · 6 · d
- Oxidation states
- +2, +4
- Electronegativity
- 2.28 (Pauling)
- Melting point
- 1,768 °C
- Boiling point
- 3,825 °C
- Density
- 21.46 g/cm³
- State at 20 °C
- Solid
- Appearance
- Lustrous, silvery-white metal
- Discovered
- Antonio de Ulloa, 1735
78 protons, and 78 electrons when neutral
IUPAC standard atomic weight
Nickel group
What Platinum is used for
- Catalytic converters and fuel cells
- Chemotherapy drugs (cisplatin)
- Laboratory crucibles and electrodes
- Jewellery
Atomic structure of Platinum
A neutral platinum atom has 78 protons and 78 electrons. Its most common isotope carries about 117 neutrons, which is where the mass number 195 comes from. Change the neutron count and you have a different isotope of platinum; change the proton count and you have a different element entirely.
Those electrons fill shells from the inside out: 2, 8, 18, 32, 17, 1. In orbital notation that is [Xe] 6s¹ 4f¹⁴ 5d⁹. As a d-block element its valence count is variable, which is why it can form compounds in several oxidation states.
3D electron orbitals
See where Platinum's electrons actually are — a cloud of 26,000 points sampled from the probability density |ψ|², not a cartoon of a lobe.
Where Platinum sits in the periodic table
The d-block. Multiple stable oxidation states give them coloured compounds, catalytic ability and the strength that makes them the working metals of industry.
- Directly above: Palladium — same group, so similar chemistry with a smaller atom.
- Directly below: Darmstadtium — same group, one shell larger.
- One proton lighter: Iridium.
- One proton heavier: Gold.
Discovery and naming
Platinum was discovered by Antonio de Ulloa in 1735. Its name comes from Spanish platina, "little silver", which is also why its symbol (Pt) does not match its English name.
Keep exploring
Atomic weight from IUPAC/CIAAW; physical properties from PubChem (US National Library of Medicine). Values that have never been measured are shown as “not measured” rather than estimated.
Related Calculators
Frequently Asked Questions
What is the atomic mass of Platinum?
The standard atomic weight of Platinum is 195.08 u, as published by IUPAC's Commission on Isotopic Abundances and Atomic Weights.
How many protons, neutrons and electrons does Platinum have?
Platinum has 78 protons, because the atomic number is the proton count and that is what makes an atom Platinum at all. A neutral Platinum atom has the same number of electrons, 78. The neutron count varies by isotope; the most common one has about 117, since 195 − 78 = 117.
What is the electron configuration of Platinum?
The electron configuration of Platinum is [Xe] 6s¹ 4f¹⁴ 5d⁹. Its electrons are arranged 2, 8, 18, 32, 17, 1 across 6 shells.
Is Platinum a metal?
Yes. Platinum is classified as a transition metal, on the metallic side of the table.
What group and period is Platinum in?
Platinum is in group 10 (the nickel group), period 6, in the d-block. The group is its column and the period is its row.
What is the charge of Platinum?
Platinum most commonly forms a 2+ or 4+ ion. Like most transition metals it has several accessible oxidation states, so the charge depends on the compound.
What is the melting point of Platinum?
Platinum melts at 1,768 °C and boils at 3,825 °C. That puts it in the solids at everyday temperatures.
What is Platinum used for?
Catalytic converters and fuel cells, Chemotherapy drugs (cisplatin), Laboratory crucibles and electrodes, Jewellery. Platinum is dense, unreactive and an outstanding catalyst, which is why it sits in both catalytic converters and fuel cells.
Who discovered Platinum, and where does its name come from?
Platinum (Pt) was discovered by Antonio de Ulloa in 1735. The name comes from Spanish platina, "little silver".