Ir
Iridium is the most corrosion-resistant metal and provided key evidence for the dinosaur extinction.
Physical Properties
| Atomic Mass | 192.22 u |
| Density | 22.56 g/cm³ |
| Melting Point | 2719.0 K |
| Boiling Point | 4701.0 K |
| Appearance | Silvery-white metallic |
| State at Room Temp | Solid |
Chemical Properties
| Electronegativity | 2.2 (Pauling) |
| 1st Ionization Energy | 880.0 kJ/mol |
| Electron Affinity | 150.94 kJ/mol |
| Oxidation States | +1, +2, +3, +4, +5, +6 |
Atomic Properties
| Electron Configuration | [Xe] 4f14 5d7 6s2 |
| Atomic Radius | 136.0 pm |
| Covalent Radius | 141.0 pm |
| Van der Waals Radius | 202.0 pm |
Discovery
| Discovered By | Smithson Tennant |
| Discovery Year | 1803 |
| Location | London, England |
| Named After | Latin 'iris' meaning rainbow, for its colorful salts |
About Iridium
Iridium is a very hard, brittle, silvery-white metal resistant to all acids and molten metals. An iridium-rich layer in geological strata worldwide proved the asteroid impact that caused dinosaur extinction.
Uses & Applications
Spark plugs, crucibles for crystal growth, and deep-sea drilling pipe.
Fun Fact
A thin layer of iridium in 66-million-year-old rock worldwide proved an asteroid caused the dinosaur extinction.
Isotopes
| Mass Number | Abundance | Half-Life | Stable |
| 191 | 0.373% | - | Yes |
| 193 | 0.627% | - | Yes |
Electron Configuration
[Xe] 4f14 5d7 6s2