Iridium
Iridium is a chemical element with the symbol Ir and atomic number 77. It is a transition metal within the platinum group and is known for its hardness and brittleness. The element is silvery-white in appearance and is considered one of the densest naturally occurring metals, second only to osmium, with a density of 22.56 g/cm³.
Discovery and Name
Iridium was discovered in 1803 by the British chemist Smithson Tennant in the acid-insoluble residues of platinum ores. The name "iridium" is derived from the Greek word "iris", meaning rainbow, due to the various colors exhibited by its compounds.
Isotopes
Iridium has two naturally occurring isotopes, 191Ir and 193Ir, both of which are stable, with 193Ir being the more abundant. Additionally, there are 40 known radioisotopes, with Iridium-192 being the most significant, utilized in industrial radiography and medical treatments.
Applications
The primary applications of iridium and its alloys are in high-performance spark plugs, crucibles for the recrystallization of semiconductors at elevated temperatures, and as electrodes in the production of chlorine via the chloralkali process. Iridium compounds such as chlorides and iodides are essential in industrial catalysis.
Iridium Anomaly
The iridium anomaly refers to the unusual abundance of iridium in a layer of rock strata at the Cretaceous–Paleogene boundary. This anomaly is closely associated with the mass extinction event that eradicated the dinosaurs, supporting the hypothesis of a massive asteroid impact being a contributing factor.
Iridium Communications
Iridium Communications Inc. is an American company that operates the Iridium satellite constellation, which provides voice and data coverage to satellite phones and other communication devices. This system is crucial for providing connectivity in remote areas where traditional cell networks are unavailable.