Chemical element · reference page

78Pt

Platinum

Platinum is element 78 (Pt), located in period 6, group 10 and the d block. At room temperature its reference phase is solid. Its electron configuration is [Xe] 4f14 5d9 6s1.

Atomic number78

Standard atomic weight195.084(9)

Group10

Period6

Blockd

Electron configuration[Xe] 4f14 5d9 6s1

Electronic structure

What controls its chemistry

The d subshell participates in the chemistry of platinum. Transition metals can use electrons of similar energies in bonding, which is why variable oxidation states, coordination compounds and catalytic behaviour are common across the d block.

Its electron configuration, [Xe] 4f14 5d9 6s1, should be read together with the oxidation state of the compound: removing electrons changes which d orbitals are occupied and can alter colour, magnetism, bonding and reactivity.

Chemical forms

Compounds, ions and materials

For platinum, important chemical forms include metals and alloys, oxides, halides and coordination compounds. Variable oxidation states are common because s and d electrons have similar energies, and ligands around the metal ion can strongly alter colour, magnetism and reactivity.

Physical behaviour

State and phase changes

The reference phase at room temperature is solid. The listed density is 21.45 g/cm³. The melting point is 2 042 K (1 769 °C). The boiling point is 4 098 K (3 825 °C). Pressure, purity and crystal structure can shift measured physical properties.

Occurrence and applications

Where platinum is found and used

In practice, platinum is encountered in catalysts, jewellery and medical applications.

In practice

Examples of real uses

Catalysts

Platinum is used to accelerate chemical reactions without being consumed in the overall reaction.

Jewellery

Platinum is used for colour, corrosion resistance, rarity, polish or mechanical properties in jewellery alloys.

Medical applications

Platinum is used in selected medicines, implants, diagnostics or treatment technologies; the chemical or isotopic form is crucial.

Periodic position

What its neighbours tell us

Platinum is in period 6 and group 10. In the neighbourhood shown here, it lies between iridium and gold in the same period; palladium is above it and darmstadtium below it in the same group. These positions make it possible to compare atomic size, ionisation energy and bonding behaviour with nearby elements.

Reference data

Physical and atomic properties

Classificationtransition metal

Phase at room temperatureSolid

Electron shells2 · 8 · 18 · 32 · 17 · 1

Density21.45 g/cm³

Melting point2 042 K (1 769 °C)

Boiling point4 098 K (3 825 °C)

Pauling electronegativity2.28

First ionisation energy864kJ/mol

Electron affinity205 kJ/mol

Values describe the element or neutral atom where applicable. Physical data can depend on allotrope, pressure and measurement conditions.

History

Discovery and identification

The discovery of platinum is associated with Antonio de Ulloa. Recognition of the element, isolation of a pure sample and assignment of its modern atomic number did not necessarily occur at the same time.

Isotopes and atomic weight

How isotope composition changes the numbers

The standard atomic weight is 195.084(9). This value refers to the isotopic composition of natural terrestrial material, not to the mass of one specific atom.

Platinum has at least one stable isotope. Different isotopes have the same number of protons and therefore the same element identity, but different neutron numbers and atomic masses.

Safety

Handling and exposure

The hazards associated with platinum depend on chemical form, dose and route of exposure. Pure platinum, its ions and its compounds can have very different biological and environmental effects, so safety data should be checked for the actual substance being handled.