chemical element with symbol Ir and atomic number 77

Iridium is the 77th element on the periodic table. Its symbol is Ir and its atomic number is 77.

A small foil of Iridium

Chemistry change

Iridium is a metal. Like other metals in the platinum group, Iridium is a rare and expensive "noble metal" and is a transition metal. It looks like platinum and is found in asteroids and comets. It is exceptionally hard-wearing.

Iridium deposits are used to identify relative dates of collisions of foreign bodies. Iridium can fold and bend just like aluminum, and remains very shiny. Most iridium is found in the Americas, though some is mined in Myanmar, South Africa, and Russia. Iridium melts at 2410 °C, and boils at 4130 °C. It is the most corrosion-resistant metal.

Iridium is not needed in the body. It is used for the tips of pens. The main uses of iridium are the metal itself and its alloys.

History change

A man named Smithson Tennant first found it in the year 1803 and is was named after Iris in Greek mythology. Smithson Tennant found it in the remains when he left crude platinum in a mixture of hydrochloric acid and nitric acid.