Rhodium

Symbol: Rh
Atomic Number: 45
Atomic Weight: 102.9055
Element Classification: Transition Metal
Discovered By: William Wollaston
Discovery Date: 1803 (England)
Name Origin: Greek: rhodon (rose). Its salts give a rosy solution.

Density (g/cc): 12.41
Melting Point (K): 2239
Boiling Point (K): 4000
Appearance: Silvery white, hard metal
Atomic Radius (pm): 134
Atomic Volume (cc/mol): 8.3
Covalent Radius (pm): 125
Ionic Radius: 68 (+3e)
Specific Heat (@20C J/g mol): 0.244
Fusion Heat (kJ/mol): 21.8
Evaporation Heat (kJ/mol): 494
Thermal Conductivity (@25C W/m K):
Debye Temperature (K): n/a
Pauling Negativity Number: 2.28
First Ionizing Energy (kJ/mol): 719.5
Oxidation States: 5, 4, 3, 2, 1, 0
Electronic Configuration: [Kr] 4d8 5s1
Lattice Structure: Face-Centered Cubic (FCC)
Lattice Constant (): 3.800
Lattice C/A Ratio: n/a

Mineral Hardness [no units]: 6.0
Brinell Hardness [/MN m-2]: 1100
Vickers Hardness [/MN m-2]: 1246

Note: Rhodium is a hard metal and is relatively easy to prepare. Rhodium is, however, sensitive to surface damage in sectioning and grinding. Relatively few metallographers work with precious metals, other than those used in electronic devices.

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