Rhodium, Rh

Rhodium is a chemical element with the symbol Rh and atomic number 45. A rare silvery-white hard transition metal and a member of the platinum group, rhodium is found in platinum ores and is used in alloys with platinum and as a catalyst. It is usually the most expensive precious metal, though it is sometimes surpassed by rhenium, depending on the market.

Rhodium is a hard silvery white and durable metal that has a high reflectance. Rhodium metal does not normally form an oxide, even when heated. Oxygen is absorbed from the atmosphere at the melting point of rhodium, but on solidification the oxygen is released. Rhodium has both a higher melting point and lower density than platinum. It is not attacked by acids: it is completely insoluble in nitric acid and dissolves slightly in aqua regia. A complete dissolution of rhodium in powder form is only obtained in sulfuric acid.

Technical Data
Symbol Rh Density (20°C)/gcm3 12.39
Atomic number 45 Melting point /°C 1960
No. of naturally occurring isotopes 1 Boiling point /°C 3760
Atomic weight 102.9055 ΔHfus/kJmol-1 21.6
Electronic configuration [Kr]4d85s1 ΔHvap/kJmol-1 494
Metal radius(12-coordinate)/pm 134 ΔHf(monoatomic gas)/kJmol-1 556(+/-11)
Effective ionic radius(6-coord)/pm V 55 Electrical resistivity (20°C)/u,ohm cm 4.33
Effective ionic radius(6-coord)/pm IV 60 Ionization energy/kJmol-1 I 720
Effective ionic radius(6-coord)/pm III 66.5 Ionization energy/kJmol-1 II 1743
Electronegativity χ 2.2 Ionization energy/kJmol-1 III 2997
Evaporation Techniques
Temperature (oC) @Vap. Pressure Techniques Remarks
10-8 Torr 10-6 Torr 10-4 Torr Electron Beam Crucible Coil Boat
1277 1472 1707 Good ThO2 & Vitreous Graphite Tungsten Tungsten EB Gun preferred

Evaporation Materials
R2-5000-M pellets 6mm diameter x 6mm long

The foils are available in either rectangular or circular shape. Please enter width and length or diameter of the required foil.

Foil
R2-3001-F 0.002" (0.050mm)
R2-3003-F 0.004" (0.10mm)
R2-3005-F 0.006" (0.152mm)
R2-3007-F 0.008" (0.20mm)
Powder
R2-10000-P -20 mesh
R2-10002-P -325 mesh
R2-10003-P -200 mesh
Rods
R2-2000-R 0.0625" (1.58mm)
R2-2001-R 0.125" (3.175mm)
R2-2002-R 0.250" (6.35mm)
R2-2003-R 0.500" (12.7mm)
Sheet
R2-4001-S 0.015" (0.38mm)
R2-4002-S 0.020" (0.5mm)
R2-4003-S 0.030" (0.76mm)
R2-4004-S 0.040" (1mm)
R2-4006-S 0.060" (1.5mm)
R2-4008-S 0.125" (3.175mm)
R2-4009-S 0.250" (6.35mm)
R2-4010-S 0.375" (9.525mm)
R2-4011-S 0.500" (12.7mm)
R2-4012-S 0.750" (19.05mm)
R2-4013-S 1" (25.4mm)
Wire
R2-1000-W 0.005" (0.127mm)
R2-1003-W 0.008" (0.203mm)
R2-1007-W 0.020" (0.5mm)
R2-1009-W 0.040" (1.0mm)
R2-1011-W 0.060" (1.5mm)
R2-1013-W 0.080" (2.0mm)