| Symbol | Ir |
| Atomnummer | 77 |
| Gruppe | 9 (Kobaltgruppe) |
| Periode | 6 |
| Blok | d |
| Klassifikation | Overgangsmetal |
| Udseende | Silvery white |
| Farve | Sølv |
| Antal protoner | 77 p+ |
| Antal neutroner | 115 n0 |
| Antal elektroner | 77 e- |
| Fase ved STP | Fast |
| Massefylde | 22.56 g/cm3 |
| Atommasse | 192.217 u |
| Smeltepunkt | 2719 K 2445.85 °C 4434.53 °F |
| Kogepunkt | 4403 K 4129.85 °C 7465.73 °F |
| Fordampningsvarme | 563.58 kJ/mol |
| Elektronegativitet (Pauling Scale) | 2.2 |
| Elektronaffinitet | 150.94 kJ/mol |
| Oxidationstrin | −3, −1, 0, +1, +2, +3, +4, +5, +6, +7, +8, +9 () |
| Ioniseringsenergier |
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| Opdagelse og første isolation | Smithson Tennant (1803) |
Opdagelse af iridium 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. Joseph Louis Proust thought that the residue was graphite. 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. In 1803, British scientist Smithson Tennant analyzed the insoluble residue and concluded that it must contain a new metal. Vauquelin treated the powder alternately with alkali and acids 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". 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. He obtained dark red crystals by a sequence of reactions with sodium hydroxide and hydrochloric acid. 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. Discovery of the new elements was documented in a letter to the Royal Society on June 21, 1804. | |