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.
Iodine is found on Earth mainly as the highly water-soluble iodide I-, which concentrates it in oceans and brine pools. Like the other halogens, free iodine occurs mainly as a diatomic molecule I2, and then only momentarily after being oxidized from iodide by an oxidant like free oxygen. In the universe and on Earth, iodine's high atomic number makes it a relatively rare element.