Iridium
Iridium | |
---|---|
Properties | |
Atomic symbol | Ir |
Atomic number | 77 |
Classification | Transition Metals |
Atomic mass | 192.22 amu |
Number of Stable Isotopes | 2 |
Density (grams per cc) | 22.560 g/cm^3 |
Other Information | |
Date of discovery | 1803 |
Name of discoverer | Smithson Tennant |
Name origin | From the Latin iridis, meaning rainbow. |
Uses | Used in conjunction with osmium to tip gold pen points, to make crucibles and other high-temperature containers. Also used to make alloys for standard weights and measures, as well as heat-resistant alloys. In addition, used in cancer irradiation, hypodermic needles, helicopter spark plugs and as hardening agent for platinum. |
Obtained from | Found in gravel deposits with platinum, iridosmium, and osmiridium ores. |
Iridium is an element in the transition metals class of the periodic table. It is hard and lustrous, and is perhaps the most corrosion-resistant metal known. It has the second-highest density of all elements, after osmium.
An alloy of platinum and iridium was used in the international standard meter bar, before the standard was changed in 1960. A similar alloy is still used in the international standard kilogram. An alloy of 90% platinum and 10% iridium is widely used in both the jewelry and chemical industries, because it is strong, hard, beautiful, and impervious to almost all chemicals even at very high temperatures.
A layer of iridium in certain rocks, found all over the world, is part of the evidence implying that an asteroid strike caused the Cretaceous-Tertiary Mass Extinction.
Uses
Iridium does not have many "everyday" uses, but a few common ones are:
- Spark plugs.
- Phonograph needles.
- It forms an alloy with osmium used for tipping pens and compass bearings.
- Electrical contacts.
See also
References
Periodic Table of the Elements | ||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | |||||||
77
Ir 192.2 |
||||||||||||||||||||||||
*Lanthanides | ||||||||||||||||||||||||
**Actinides | ||||||||||||||||||||||||