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Discovered in 1803 by W.H. Wollaston at London, England.
[Greek, rhodon = rose]
French: rhodium
German: Rhodium
Italian: rodio
Spanish: rodio
Description: Rhodium is a rare, lustrous, silvery, hard metal of the so-called platinum group. It is unaffected by air and water up to 875 K, and unaffected by acids, but is attacked by molten alkalis. Rhodium is used as a catalyst.
State: | single crystal |
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Crystal structure: | fcc |
Production method: | Floating Zone |
Standard size: | diameter 6-10mm thickness 1-2mm |
Orientation: | (100), (110) and (111) |
Orientation accuracy: | <2°, <1°, <0.4° or <0.1° |
Polishing: | as cut, one or two sides polished |
Roughness of surface: | <0.03µm |
Purity: | 99.99% |
Typical analysis (ppm): | C 3 H < 1 O 9 N < 5 Cu 1.60 Fe 1.80 Ni < 1 Pb 0.30 Si 0.30 Ga, Hf and Ta are below the detection limit |
Density: | 12.4 g/cm3 |
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Melting point: | 1965.85 °C / 2239 °K |
Boiling point: | 3726.85 °C / 4000 °K |
Molar volume: | 8.29 cm3 |
Thermal conductivity: | 150 [300 K] Wm-1K-1 |
Coefficient of linear thermal expansion: | 8.40 x 10-6 K-1 |
Electrical resistivity: | 4.51x 10-8 [293 K] Wm |
Mass magnetic susceptibility: | +1.36 x 10-8(s) kg-1m3 |
Young's modulus: | 379 GPa |
Rigidity modulus: | 147 GPa |
Bulk modulus: | 276 GPa |
Poisson's ratio: | 0.26 |
Radii: | Rh4+ 67; Rh3+ 75; Rh2+ 86; atomic 134; covalent 12 |
Electronegativity: | 2.28 (Pauling); 1.45 (Allred); 4.30 eV (absolute) |
Effective nuclear charge: | 3.90 (Slater); 7.64 (Clementi); 10.85 (Froese-Fischer) |
Number of Isotopes (incl. nuclear isomers): | 34 |
Issotope mass range: | 94m -> 112 |
Crystal structure, (cell dimentions / pm), space group | fcc |
X-ray diffraction: mass absorption coefficients: | CuKα 194 (µ/r) / cm2g-1 MoKα 22.6 (µ/r) / cm2g-1 |
Neutron scattering length: | 0.588 b/10-12 cm |
Thermal neutron capture cross-section: | 144.8 sa / barns |
Biological role: | none |
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Toxicity | |
Toxic intake: | most rhodium compounds are slightly toxic by ingestion. |
Lethal intake: | LD50 (RhCl3, ortal, rat)= 12.6 mg kg-1 |
Hazards: | There are few reported cases of humans being affected by rhodium, but it is an experimental carcinogen. |
Level in humans | |
Blood: | |
Bone: | |
Liver: | |
Muscle: | |
Daily dietary intake: | n.a. |
Total mass of element in average [70 kg] person: | n.a. |
Mineral | Formula | Density | Hardness | Crystal apperance |
---|---|---|---|---|
Rhodium | Rh | c. 12 | 3.5 | cub., met. white |
Rhodplumsite | Ph3Pb2S2 | 9.74 | n.a. | rhom., met. cream-pink/grey-blue |
Chief ore: | native rhodium is found in Montana, USA; certain copper and nickel ores contain up to 0.1% rhodium a |
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World production: | 3 tonnes/year |
Main mining areas: | see copper and nickel |
Reserves: | n.a. |
Specimen: | available as foil, sponge or wire. Safe. |
Abundances | |
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Sun: | 25.1 (relative to H = 1 x 1012) |
Earth's crust: | 2 x 10-4 p.p.m. |
Seawater: | |
Residence time: | |
Classification: | |
Oxidation state: |
Source: Emsley, J. (1998) The Elements (3rd Edition)