Two common examples are osmiridium and iridosmine, combinations of iridium and osmium. Iridium usually occurs in combination with one or more other noble metals. Stony meteorites contain less iridium, about 0.64 parts per million. Iron meteorites, for example, generally contain about 3 parts per million of iridium. Interestingly, it is more abundant in other parts of the universe. It is thought to exist in two parts per billion. Iridium is one of the rarest elements in the Earth's crust. Then it reacts with oxygen and halogens to form iridium dioxide and iridium trihalides. When exposed to air, it reacts with oxygen to form a thin Layer of iridium dioxide (IrO 2).Īt high temperatures, the metal becomes more reactive. Iridium is unreactive at room temperatures. Therefore, it is usually shaped at high temperatures. Ductile means capable of being drawn into thin wires. It becomes more ductile (flexible) when hot. Cold iridium metal cannot be worked easily. Iridium has a melting point of 2,443 ☌ (4,429 ☏) and a boiling point of about 4,500 ☌ (8,130 ☏). A cubic centimeter of iridium weighs 22.65 times as much as a cubic centimeter of water. Iridium metal is silvery-white with a density of 22.65 grams per cubic centimeter. For example, iridium potassium chloride (K 2IrCl 6) is dark red, iridium tri-bromide (IrBr 3) is olive-green, and iridium trichloride (IrCl 3) is dark green to blue-black. Tennant chose this name because the compounds of iridium have so many different colors. He named it iridium, from the Greek goddess Iris, whose symbol is a rainbow. He realized he had discovered a new element. He discovered that it had properties very different from those of platinum. Other chemists had not bothered to study the powder. He found that most of the platinum metal dissolved, leaving a small amount of black powder. Aqua regia is a mixture of two strong acids - nitric acid and hydrochloric acid. In 1803, Tennant attempted to dissolve platinum in aqua regia. He is said to have made gunpowder to use in fireworks when he was only nine years old! Like so many others, Tennant became interested in chemistry at an early age. One of those chemists was an Englishman named Smithson Tennant (1761-1815). In the early 1800s, a number of chemists worked to separate the platinum metals. Chabaneau did not realize that the "platinum" he was studying included various amounts of other noble metals. At other times, it was brittle and shattered when hammered. Sometimes the platinum he worked with could be hammered into flat plates easily. In the late 1780s, the Spanish government gave its entire supply of platinum to Chabaneau to study. The work of French chemist Pierre-Fran çois Chabaneau is an example. Of platinum, the sample often contained iridium, rhodium, osmium, and other metals as well. When a scientist thought that he was analyzing a sample These metals often occurred mixed together in the earth. The platinum metals posed a difficult problem for early chemists. PRONUNCIATION i-RI-dee-um Discovery and naming Scientists search for iridium in the soil to track the impact of a giant meteor with the Earth 65 million years ago.įAMILY Group 9 (VIIIB) Transition metal Platinum group Iridium may be a key element in the puzzle of dinosaur extinction. That property makes it useful in making objects that are exposed to such materials. It is not affected by high temperatures, acids, bases, or most other strong chemicals. In fact, iridium is the most corrosion-resistant metal known. They appear to be "too superior" to react with most other substances. They have this name because they do not react well with other elements and compounds. The metals in the platinum family are also known as the noble metals. Indium is a transition metal that is also part of the platinum family. The periodic table is a chart that shows how elements are related to one another. Indium is in Group 9 (VIIIB) of the periodic table. Note: This article, originally published in 1998, was updated in 2006 for the eBook edition.
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