{"id":125,"date":"2020-04-08T15:06:23","date_gmt":"2020-04-08T15:06:23","guid":{"rendered":"https:\/\/thechemicalelements.com\/?page_id=125"},"modified":"2023-08-16T08:40:43","modified_gmt":"2023-08-16T08:40:43","slug":"rhodium","status":"publish","type":"post","link":"https:\/\/thechemicalelements.com\/rhodium\/","title":{"rendered":"Rhodium (Rh)"},"content":{"rendered":"\n

Rhodium is a chemical element with the atomic number 45 in the periodic table. It\u2019s an extremely rare metal that is found in Earth\u2019s crust with an abundance of 0.0002 parts per million.\u00a0<\/span><\/p>\n\n\n\n

Being a member of the platinum<\/a> group of periodic table elements, this noble metal has three valence electrons and is highly appreciated for its corrosion and oxidation resistance, bright lustrous shine, as well as for its durability as a material.\u00a0<\/span><\/p>\n\n\n\n

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Chemical and Physical Properties of Rhodium<\/span><\/h3>\n\n\n\n
Property<\/strong><\/td>Value<\/strong><\/td><\/tr>
Symbol<\/td>Rh<\/td><\/tr>
Name<\/td>Rhodium<\/td><\/tr>
Atomic number<\/td>45<\/td><\/tr>
Atomic weight<\/td>102.9055 g.mol-1<\/td><\/tr>
Group<\/td>Transition Metal<\/td><\/tr>
Period<\/td>5 (d-block)<\/td><\/tr>
Color<\/td>A precious silver-white metal<\/td><\/tr>
Physical state<\/td>Solid at room temperature<\/td><\/tr>
Electronegativity<\/td>2.28<\/td><\/tr>
Density<\/td>12.4 g.cm-3 at 20\u00b0C<\/td><\/tr>
Melting point<\/td>1963\u00b0C, 3565\u00b0F, 2236 K<\/td><\/tr>
Boiling point<\/td>3695\u00b0C, 6683\u00b0F, 3968 K<\/td><\/tr>
Ionic radius<\/td>75 (3+) pm<\/td><\/tr>
Isotopes<\/td>33<\/td><\/tr>
Most characteristic isotope<\/td>rhodium-103<\/td><\/tr>
Electronic shell<\/td>[Kr] 4d8 5s1<\/td><\/tr>
The energy of the first ionization<\/td>742 kJ.mol-1<\/td><\/tr>
Discoverer<\/td>William Wollaston<\/td><\/tr>
Year<\/td>1803<\/td><\/tr>
Uses<\/td>Used as a coating to prevent wear on high-quality science equipment and with platinum to make thermocouples.<\/td><\/tr>
Description<\/td>Soft, malleable, ductile, silvery-white metal.<\/td><\/tr>
Shells<\/td>2,8,18,16,1<\/td><\/tr>
Valence<\/td>2,3,4,5,6<\/td><\/tr>
Crystal Structure<\/td>Cubic: Face centered<\/td><\/tr>
Covalent Radius<\/td>1.25 \u00c5<\/td><\/tr>
Atomic Radius<\/td>1.83 \u00c5<\/td><\/tr>
Atomic Volume<\/td>08.3 cm\u00b3\/mol<\/td><\/tr>
Name Origin<\/td>Greek: rhodon (rose). Its salts give a rosy solution.<\/td><\/tr>
Location<\/td>England<\/td><\/tr>
Pronounced<\/td>RO-di-em<\/td><\/tr>
Oxydation States<\/td>2,(3),4<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
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With the periodic table symbol Rh, atomic number 45, atomic mass of 102.91g.mol-1, and electron configuration [Kr] 4d8 5s1, rhodium is a hard, silvery-white precious metal that does not tarnish upon exposure to air.\u00a0<\/span><\/p>\n\n\n\n

It reaches its boiling point at 3695\u00b0C, 6683\u00b0F, 3968 K, while the melting point is achieved at 1963\u00b0C, 3565\u00b0F, 2236 K. This member of the platinum family of elements in the periodic table has an electronegativity of 2.2 according to Pauling, whereas the atomic radius according to van der Waals is unknown.\u00a0<\/span><\/p>\n\n\n\n

Classified as a transition metal, rhodium has strong anti-corrosive properties and has the capacity to resist extremely high temperatures. It\u2019s also characterized by a lower density and a higher melting point than platinum.<\/span><\/p>\n\n\n\n

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How Was Rhodium Discovered?<\/span><\/h2>\n\n\n\n

Element 45 was discovered in 1804 by the English chemist and physicist William Hyde Wollaston (1766 \u2013 1828). After the French chemist Hippolyte-Victor Collet-Descotils expressed his belief that a sample of platinum ore obtained from South Africa could possibly contain a new metal, he supported his claim by pointing to the presence of the red color of some platinum salts.<\/span><\/p>\n\n\n\n

This triggered Wollason\u2019s scientific curiosity, so he took a closer look at the platinum sample. First, the English chemist dissolved crude platinum in aqua regia, after which he precipitated platinum metal by dissolving the solution in ammonium chloride.\u00a0<\/span><\/p>\n\n\n\n

The remaining liquid substance was furthermore included in several other chemical reactions, after which Wollaston succeeded in producing a deep red powder, i.e sodium<\/a> rhodium chloride. In the last step of this series of chemical reactions, the rhodium precipitate was treated with zinc<\/a>. Finally, the presence of the new element 45 in the platinum ore was evident and confirmed.\u00a0<\/span><\/p>\n\n\n\n

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How Did Rhodium Get Its Name?<\/span><\/h2>\n\n\n\n

The name of this chemical element comes from the Greek word ‘<\/span>rhodon<\/span><\/i>‘, meaning \u2018<\/span>rose colored<\/span><\/i>\u2019. This refers to the characteristic rose-red color of the rhodium salts.\u00a0<\/span><\/p>\n\n\n\n

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Where Can You Find Rhodium?<\/span><\/h2>\n\n\n\n

As a member of the platinum group, rhodium mostly occurs in the same mineral ores as the other platinum metals, such as platinum, palladium<\/a>, nickel<\/a>, silver<\/a>, and gold<\/a>. It can be isolated from the minerals bowieite, rhodite, and rhodplumsite, in which rhodium occurs as a part of a compound.\u00a0<\/span><\/p>\n\n\n\n

Primary rhodium mines are rarely found. Thus, this rare metal is typically obtained as a by-product of platinum and palladium mining or nickel mining. It can also be traced in the native alloys of iridium (at least 11.25 percent) and osmium<\/a> in iridosmine (at least 4.5 percent in siserskite).\u00a0<\/span><\/p>\n\n\n\n

For commercial purposes, element 45 is mostly isolated as a by-product of the extraction of nickel and copper<\/a> from their ores. South Africa, South America, Canada, and Russia, are the world’s leading rhodium producers. The price of rhodium is typically high, but also highly variable on the precious metals market.\u00a0<\/span><\/p>\n\n\n\n

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Rhodium in Everyday Life<\/span><\/h2>\n\n\n\n

Rhodium is a noble metal praised for its superb anti-corrosive properties, as well as for its thermal and oxidation resistance. The practical uses of this rare chemical with a high price can be observed in the following instances:<\/span><\/p>\n\n\n\n