078Transition metal · Group 10 · Period 6

Platinum

Platinum (Pt) is element 78, a transition metal in the d-block — group 10, period 6. It is a solid at room temperature with 6 electron shells (2, 8, 18, 32, 17, 1) and an atomic mass of 195.0849 u.

Atomic mass: 195.1 u
Phase · STP: solid
Melting: 2041 K · 1768 °C
Boiling: 4098 K · 3825 °C
Electronegativity: 2.28
Density: 21.45 g/cm³

Photograph — Periodictableru, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

Identity

Atomic number: 78
Standard atomic weight: 195.1 u
Category: Transition metal
Group: 10
Period: 6
Block: d-block
Oxidation states: +4, +2

Physical properties

Melting point: 2041 K · 1768 °C
Boiling point: 4098 K · 3825 °C
Density: 21.45 g/cm³
Molar heat capacity: 25.86 J/(mol·K)
Atomic radius: 209 pm
Electron affinity: 205.041 kJ/mol

Atomic structure

78protons

117neutrons

78electrons

1valence e⁻

Noble-gas notation: [Xe] 4f14 5d9 6s1
Full configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s1 4f14 5d9
Electrons per shell: 2, 8, 18, 32, 17, 1

Periodic trends

Where Platinum ranks across all 118 elements.

Electronegativity2.28

Ionization energy870 kJ/mol

Electron affinity205.041 kJ/mol

Density21.45 g/cm³

Atomic radius209 pm

Ionization energies

Energy to remove each successive electron (kJ/mol).

870

1.8k

Successive ionization energies (kJ/mol, log scale).

Discovery

Discovered: 1735
Discovered by: Antonio de Ulloa
Named by: —
Appearance: silvery white