Iridium and Osmium Discover - Periodic Table of Videos

Iridium

The discovery of iridium is intertwined with that of platinum and the other metals of the platinum group. Native platinum used by ancient Ethiopians^[30] and by South American cultures^[31] always contained a small amount of the other platinum group metals, including iridium. Platinum reached Europe as platina ("silverette"), found in the 17th century by the Spanish conquerors in a region today known as the department of Chocó in Colombia.^[32] The discovery that this metal was not an alloy of known elements, but instead a distinct new element, did not occur until 1748.^[33]
Chemists who studied platinum dissolved it in aqua regia (a mixture of hydrochloric and nitric acids) to create soluble salts. They always observed a small amount of a dark, insoluble residue.^[6] Joseph Louis Proust thought that the residue was graphite.^[6] The French chemists Victor Collet-Descotils, Antoine François, comte de Fourcroy, and Louis Nicolas Vauquelin also observed the black residue in 1803, but did not obtain enough for further experiments.^[6]
In 1803, British scientist Smithson Tennant (1761–1815) analyzed the insoluble residue and concluded that it must contain a new metal. Vauquelin treated the powder alternately with alkali and acids^[12] and obtained a volatile new oxide, which he believed to be of this new metal—which he named ptene, from the Greek word πτηνός ptēnós, "winged".^[34][35] Tennant, who had the advantage of a much greater amount of residue, continued his research and identified the two previously undiscovered elements in the black residue, iridium and osmium.^[6][12] He obtained dark red crystals (probably of Na
2[IrCl
6]·nH
2O) by a sequence of reactions with sodium hydroxide and hydrochloric acid.^[35] He named iridium after Iris (Ἶρις), the Greek winged goddess of the rainbow and the messenger of the Olympian gods, because many of the salts he obtained were strongly colored.^{[note 2][36]} Discovery of the new elements was documented in a letter to the Royal Society on June 21, 1804.^[6][37]

Osmium

Osmium was discovered in 1803 by Smithson Tennant and William Hyde Wollaston in London, England.^[31] The discovery of osmium is intertwined with that of platinum and the other metals of the platinum group. Platinum reached Europe as platina ("small silver"), first encountered in the late 17th century in silver mines around the Chocó Department, in Colombia.^[32] The discovery that this metal was not an alloy, but a distinct new element, was published in 1748.^[33] Chemists who studied platinum dissolved it in aqua regia (a mixture of hydrochloric and nitric acids) to create soluble salts. They always observed a small amount of a dark, insoluble residue.^[27] Joseph Louis Proust thought that the residue was graphite.^[27] Victor Collet-Descotils, Antoine François, comte de Fourcroy, and Louis Nicolas Vauquelin also observed the black residue in 1803, but did not obtain enough material for further experiments.^[27]
In 1803, Smithson Tennant analyzed the insoluble residue and concluded that it must contain a new metal. Vauquelin treated the powder alternately with alkali and acids^[34] and obtained a volatile new oxide, which he believed to be of this new metal—which he named ptene, from the Greek word πτηνος (ptènos) for winged.^[35][36] However, Tennant, who had the advantage of a much larger amount of residue, continued his research and identified two previously undiscovered elements in the black residue, iridium and osmium.^[27][34] He obtained a yellow solution (probably of cis–[Os(OH)₂O₄]²⁻) by reactions with sodium hydroxide at red heat. After acidification he was able to distill the formed OsO₄.^[35] He named it osmium after Greek osme meaning "a smell", because of the ashy and smoky smell of the volatile osmium tetroxide.^[37] Discovery of the new elements was documented in a letter to the Royal Society on June 21, 1804.[