iridium (Ir)
A very hard and brittle, exceptionally corrosion-resistant,
silvery-white metallic element. Iridium
is a transition element and a
member of the platinum group. It
occurs in platinum ore and is used principally
to harden platinum and in high-temperature materials, surgical and scientific
instruments, electrical contacts, pen tips, and and wear-resistant bearings.
It is also used to encapsulate radioactive fuels on spacecraft. Discovered
by Smithson Tennant in London in 1803, its name comes from the Latin iris
(stem irid-) for "rainbow," from the variety of colors in gives
in solution. Its most common isotope is
193Ir (62.6%).
| atomic number |
77 |
| relative atomic mass |
192.2 |
| relative density |
22.42 (at 17°C) |
| melting point |
2,140°C |
| boiling point |
4,527°C |
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INORGANIC
CHEMISTRY
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