Atoms of the same element are identical. The atoms of the one element are different from those of any other element. 3. Atoms of different elements can physically mix together or can chemically combine in simple whole-number ratios to form compounds.
iridium (symbol Ir) Silver-white, metallic element discovered in 1804 by the English chemist Smithson Tennant. A platinum-type metal, iridium is hard and brittle and the most corrosion-resistant metal. very rare element (0.0001 ppm of Earth 's crust), iridium is found in the naturally occurring alloys osmiridium (approximately 50% iridium) and iridiosmium (approximately 70% iridium) in Alaska and South Africa. It is obtained by igniting ammonium chloroiridate, (NH 4) 3 IrCl 6, in hydrogen atmosphere.
Iridium was originally found as a contaminant (with the element osmium) in platinum, and it was from the solid remnants left when platinum was dissolved in a mix of sulphuric and hydrochloric acids that Tennant made his discovery of both elements.t has a very high density and melting point. Uses. Iridium is the most corrosion-resistant material known. It is used in special alloys and forms an alloy with osmium, which is used for pen tips and compass bearings. It was used in making the standard metre bar, which is an alloy of 90% platinum and 10% iridium.