Platinum (Pt)

Platinum is a transition metal with atomic number 78, in period 6 and group 10 of the periodic table. Its atomic mass is 195.084 u and its electron configuration is [Xe] 4f¹⁴ 5d⁹ 6s¹. Solid at 25 °C.

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Key facts

Atomic number	78
Atomic mass	195.084 u
Category	Transition Metal
Period	6
Group	10
Block	d
Electron configuration	[Xe] 4f¹⁴ 5d⁹ 6s¹
Electrons per shell	2, 8, 18, 32, 17, 1
Electronegativity (Pauling)	2.28
Oxidation states	−3, −2, −1, +1, +2, +3, +4, +5, +6common in bold
State at 25 °C	Solid
Melting point	2041.4 K1768.25 °C
Boiling point	4098 K3824.85 °C
Density	21.45 g/cm³

Atomic properties

First ionization energy	8.959 eV
Electron affinity	205.3 kJ/mol
Atomic radius	139 pm
Covalent radius	136 pm
Van der Waals radius	209 pm
Common ions	Pt⁴⁺, Pt²⁺
Protons, neutrons, electrons	78, 117, 78

Physical and thermal properties

Molar volume	9.09 cm³/mol
Heat of fusion	20 kJ/mol
Heat of vaporization	490 kJ/mol
Specific heat	133 J/(kg·K)
Thermal conductivity	71 W/(m·K)
Thermal expansion	8.9 × 10⁻⁶ K⁻¹
Mohs hardness	3.5
Young’s modulus	168 GPa
Crystal structure	Face-centered cubic
Magnetic type	Paramagnetic

Identification and history

CAS number	7440-06-4
Latin name	Platinum
Discovered by	Antonio de Ulloa · 1735
Named by	---

Natural isotopes

Isotope	Mass (u)	Abundance
¹⁹⁰Pt	189.95995	0.012 %
¹⁹²Pt	191.961043	0.782 %
¹⁹⁴Pt	193.962683	32.864 %
¹⁹⁵Pt	194.964794	33.775 %
¹⁹⁶Pt	195.964955	25.211 %
¹⁹⁸Pt	197.967897	7.356 %

Data checked against PubChem (NIH), IUPAC, the NIST Atomic Spectra Database and the IAEA (NUBASE and AME), the same data you see in the app.

A dash (---) means there is no reliable published measurement. The app never makes one up.

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