Periodic Table -> Iridium


Iridium Details

Iridium Symbol: Ir

Iridium Atomic Number: 77

Iridium Atomic Weight: 192.217

What is Iridium?

Iridium (symbol Ir, atomic number 77) is a chemical element and a slivery-white, brittle, and very hard transition metal. It is the most corrosion-resistant metal, and the second-densest element, belonging to the platinum family. While some halogens and molten salts are corrosive to iridium, it can be flammable and is more reactive when in the form of iridium dust.

Iridium was discovered by Smithson Tennant in 1803, who named the element after the goddess Iris. The scientists who studied it created soluble salts by dissolving the element in a mixture of nitric and hydrochloric acids (aqua regia). The French chemists Louis Nicolas Vauquelin, Antoine François, and Victor Collet-Descotils observed the element as well, but they didn’t obtain quantities large enough to continue research.

This element is among the rarest found in the earth’s crust, and the total production and consumption per year is about 3 tonnes. The only isotopes of iridium, which occur naturally, are 193Ir and 191Ir, and they are also the only stable isotopes of the element. Iridium-193 is more abundant than iridium-191.

In its pure form, the element is very hard to machine and very brittle. The main application of iridium is as a hardening agent of platinum. High temperature equipment such as crucibles is made from platinum-iridium alloys. Alloys made of osmium and iridium are used to produce elements of fountain pens.

Given that this element is corrosive-resistant, an alloy of 10 percent iridium and 90 percent platinum was used to create the standard meter bar. In fact, most of the applications of iridium are based on its corrosion resistance, hardness, and high melting point. Iridium, osmium-iridium alloys, and iridium-platinum alloys are used to make multi-pored spinnerets. Osmium- iridium alloys are used for balances and compass bearings. Heat resistance and corrosion make this element a good alloying agent.
Deep-water pipes are made using an iridium-titanium alloy due to its corrosion resistance, and an iridium alloy is used to make certain long-life parts for aircraft engines. In platinum alloys, the element is employed as a hardening agent. In addition, thermoelectric generators are produced using iridium. They are made for unmanned spacecraft like Pioneer, Viking, Voyager, Galileo, Cassini, and New Horizons. Plutonium-238 fuel is encapsulated using iridium because of its great strength and ability to withstand temperatures of 2000 °C.

Iridium is mostly used in the chemical, automotive, and electronic industry. It has application in special and scientific equipment and in pivot bearings, but it is mainly employed in alloys.

In the environment, iridium can be found in idrosmine, iridium-osmium alloys, and as an uncombined element. Most of the iridium nowadays in found on the territory of South Africa. The reserves of iridium have not been estimated. This element is highly flammable and if it comes in contact with the eyes, it may cause irritation. Standard industrial handling poses low hazard when it comes to skin contact, but ingestion of iridium may cause irritation. It is, however, a low ingestion hazard. Products should not be allowed to reach the sewage system, water bodies, and ground water.

Little is known about the level of toxicity of iridium compounds because they are not used in large amounts. However, iridium halides and other soluble salts can be hazardous. Most compounds of iridium are insoluble, making absorption difficult.

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