Editorial Feature

Platinum Group Metals - Comparison of Physical Properties

Native South Americans were familiar with platinum even before the arrival of Columbus and the metal was introduced into Europe around 1750.

Platinum is a member of the platinum group metals and is ductile, malleable, and lustrous; it is found on earth’s crust with an abundance of approximately 0.001 ppm.

Platinum is the most important of the group of six metals (Pt, Pd, Os, Ir, Rh and Ru). It is non-reactive with oxygen and water and is only soluble in fused alkalis or aqua regia.


Platinum has a number of applications, for instance, it is employed to make measures standards and weights, it is employed to make electrodes which might be subject to chemical attack, and it is employed in the electronics industry to make electrical contacts which might be subject to elevated temperatures.

A current and key application of platinum is in car exhaust catalysts, where in platinum coating is applied on a ceramic honeycomb. Platinum is also employed to make jewelry and, like silver and gold, has its own hallmark.

Car exhaust catalysts are one of many applications which use Paltinum. Image Credits: shutterstock.com/chanonnatsrisura

Physical and Mechanical Properties

Physical and mechanical properties for the platinum group of metals in the Periodic Table of Elements.

Platinum Iridium Osmium Palladium Rhodium Ruthenium Gold Silver
Chemical Symbols Pt Ir Os Pd Rh Ru Au Ag
Atomic Number 78 77 76 46 45 44 79 47
Atomic Weight 195.09 192.22 190.2 106.4 102.9055 101.07 196.967 107.87
Density g/cm3 21.45 22.65 22.61 12.02 12.41 12.45 19.3 10.5
Melting Point C 1769 2443 3050 1554 1960 2310 1064.43 961.93
Vickers Hardness (annealed) 41 220 -- 41 101 -- 20 26
Electrical Resistivity at 0 C microohm.cm 9.85 4.71 8.12 9.93 4.33 6.80 2.4 1.6
Thermal Conductivity Watts/meter/C 73 148 87 76 150 105 293 419
Tensile Strength (annealed) tons per square inch 9 71 -- 11 45 36 7 9

*FCC - face-centred cubic, HCP - hexagonal close-packed

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