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#77 |
of Mill Valley Middle School |
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Iridium was first discovered by the British scientist Smithson Tennant in 1803 in London, UK. It was found in the residue lift by platinum that had been dissolved by aqua regia. Iridium was then appropriatly named after the latin word for 'iris' or 'rainbow' because of it's highly colorful salts. |
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Iridium is found uncombined in nature with platinum and other members of this family in alluvial deposites. It is recovered as a by-product from the nickel mining industry. It is also found in in gravel deposits with platinum. |
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Iridium is a metal of the platinum family, it is white and similar to plantinum but with a slight yellowish cast. It is hard and brittle, so therefore hard to work and form. It is the most corrosion resistent metal know, it was used in making the standard meter bar of Paris, which is 90% platinum and 10% iridium alloy. (This meter bar was replaced in 1960.) Iridium is not corroded by acids or aqua regia, but is attacked by molten salts such as NaCl and NaCN. It is stable to air and water. |
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Iridium is used as a hardening agent for platinum and is used in special alloys and spark plugs as high grade as the ones used in helicoptors. Iridium is used in satalites, thruster engines, hypodermic needles, to tip gold pens, crucibles, and some special scientific containers. |
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The extremely hard, metalic element iridium is so rare that in the order of abundance it ranks 77th. Iridium is considered the most dense element on the planet aside from osmium, which despite many test, they are still inconclusive on which is more dense. Iridium melts at about 2410 degrees C, which is about 4370 degrees F, and it boils at about 4130 degrees C, which is about 7466 degrees F. It has a gravity of 22.6, and it's atomic weight is 192.22. Iridium flares light of in space and put on a lovely show. Iridium can also be found in spaceships. |
Element: Iridium Chemical Symbol: Ir Number of Electrons: 77 Number of Protons: 77 Number of Neutrons: 115 State at Room Temp.: Solid Melting Point: 2683 Kelvin Boiling Point: 4403 Kelvin Gravity: 22.6 Atomic Weight: 192.22 |
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Glossary:Taken from Dictionary.com dissolved: "1.To cause to pass into solution: dissolve salt in water. 2.To reduce (solid matter) to liquid form; melt. 3.To cause to disappear or vanish; dispel. 4.To break into component parts; disintegrate. 5.To bring to an end by or as if by breaking up" aqua regia: "A corrosive, fuming, volatile mixture of hydrochloric and nitric acids, used for testing metals and dissolving platinum and gold. Also called nitrohydrochloric acid." alluvial deposites: "Sediment deposited by flowing water, as in a riverbed, flood plain, or delta. Also called alluvion." corrosion resistent: "To be imume to being a metal or alloy gradually, especially by oxidation or chemical action destroyed: acid corroding metal."
alloy: "A homogeneous mixture or solid solution of two or more metals, the atoms of one replacing or occupying interstitial positions between the atoms of the other: Brass is an alloy of zinc and copper." osmium: "A bluish-white, hard metallic element, found in small amounts in osmiridium, nickel, and platinum ores. It is used as a platinum hardener and in making pen points, phonograph needles, and instrument pivots. Atomic number 76; atomic weight 190.2; melting point 3,000°C; boiling point 5,000°C; specific gravity 22.57; valence 2, 3, 4, 8." |
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