Discovery date : 1803
Discovered by: William Hyde Wollaston
Origin of the name: The name is derived from the Greek 'rhodon', meaning rose coloured.
Allotropes :
~>RHODIUM is a chemical element with symbol Rh and atomic number 45. It is a rare, silvery-white, hard, corrosion resistant and chemically inert transition metal. It is a noble metal and a member of the platinum group.
| FACT BOX | |||
| Group | 9 | Melting point | 1963°C, 3565°F, 2236 K |
| Period | 5 | Boiling point | 3695°C, 6683°F, 3968 K |
| Block | d | Density (g cm−3) | 12.4 |
| Atomic number | 45 | Relative atomic mass | 102.906 |
| State at 20°C | Solid | Key isotopes | 103Rh |
| Electron configuration | [Kr] 4d85s1 | CAS number | 7440-16-6 |
| ChemSpider ID | 22389 | ChemSpider is a free chemical structure database | |
Rhodium was discovered in 1803 by William Wollaston. He collaborated with Smithson Tennant in a commercial venture, part of which was to produce pure platinum for sale. The first step in the process was to dissolve ordinary platinum in aqua regia (nitric acid + hydrochloric acid). Not all of it went into solution and it left behind a black residue. (Tennant investigated this residue and from it he eventually isolated osmium and iridium.) Wollaston concentrated on the solution of dissolved platinum which also contained palladium. He removed these metals by precipitation and was left with a beautiful red solution from which he obtained rose red crystals. These were sodium rhodium chloride, Na3RhCl6. From them he eventually produced a sample of the metal itself.