Iridium (Ir): Atomic number: 77, Atomic mass: 192.2 g.mol -1, Electronegativity: 2.2, Density: 22.4 g.cm-3 at 20°C, Melting point: 2450 °C, Boiling point: 4527 °C, Vanderwaals radius: 0.126 nm, Ionic radius: 0.066 nm (+4), Isotopes: 11, Electronic shell: [ Xe ] 4f14 5d7 6s2, Energy of first ionisation: 886 kJ.mol -1, Standard potential: + 1.0 V ( Ir2+/ Ir ), Discovered by: Smithson Tennant in 1804. Iridium is a hard, brittle, lustrous, dense, transition metal of the platinum family. It is silvery-white and it is notable for being the most corrosion resistant element known. It is unaffected by air, water and acids. Applications: Nowadays demand for iridium comes mainly from the electronic industry, the automotive industry and from the chemical industry, where it is used to coat the electrodes in the chlor-alkali process, and in catalyst. Some applications are in pivot bearings and in scientific and other special equipment, but it is principally used in alloys: osmium/iridium alloys are used for tipping fountain pen nibs and for compass bearings. Iridium in the environment: The level of iridium in land plants is below 20 ppb. Iridium is found as uncombined element, and also as the iridium-osmium alloys osmiridium and idrosmine. Most of the iridium comes from South Africa. Annual world production amounts to around 3 tonnes. Reserves have not been estimated. Health effects of iridium: Highly flammable. Potential health effects: Eye: may cause eye irritation. Skin: low hazard for usual industrial handling. Ingestion: may cause irritation of the digestive tract. Expected to be a low ingestion hazard. Inhalation: low hazard for usual industrial handling. Environmental effects of iridium: Do not allow product to reach ground water, water bodies or sewage system.

 

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Iridium (Ir): Atomic number: 77, Atomic mass: 192.2 g.mol -1, Electronegativity: 2.2, Density: 22.4 g.cm-3 at 20°C, Melting point: 2450 °C, Boiling point: 4527 °C, Vanderwaals radius: 0.126 nm, Ionic radi . . . View Full Definition

Iridium: First LEO-based global communications system backed by Motorola. Built primarily for voice transmissions, it was launched in 1998 and went into Chapter 11 in 1999.