Rhodium, Physical and Chemical Properties

Rhodium is a member of the group of six platinum metals which occur together in nature and is located in the center of the Periodic Table in the Iron-Cobalt-Nickel group:

Fe	Co	Ni
Ru	Rhodium	Pd
Os	Ir	Pt

Physical Properties

Atomic number	45
Atomic weight	102.91
Relative abundance in Earth’s crust, %	1 × 10−7
Abundance of major natural isotopes	103 (100%)
Crystal structure	Face-centered cubic
Lattice constants at 20°C	0.38031
a, nm
c, nm
Atomic radius, nm	0.134
Melting point, °C	1,966
Boiling point, °C	3,760
Specific heat at 25°C c p, J g−1 K−1	0.24
Thermal conductivity λ, W m−1 K−1	89
Density at 20°C, g/cm3	12.41
Brinell hardness	101
Young’s modulus E, N/mm2	379,058
Tensile strength σB, N/mm2	412
Specific electrical resistance at 0°C, μΩ cm	4.33
Temperature coefficient of electrical resistance (0–100°C), K−1	0.0046
Thermoelectric voltage versus Pt at 100°C E, V	+0.70

Chemical Properties

Because of the small energy differences between the valence shells, a number of oxidation states...