Ir
Iridium
Atomic number: 77Mass: 192.217 uCategory: Transition Metal
About Iridium
Iridium is a very hard, brittle, silvery-white transition metal of the platinum group. It has the second highest density and the highest corrosion-resistance of all metals. A thin layer of iridium marks the Cretaceous-Paleogene boundary.
Properties
Period
6
Group
9
Block
D
Category
Transition Metal
Electronegativity
2.20 (Pauling)
Ionization Energy
880 kJ/mol
Melting Point
2719 K (2446°C)
Boiling Point
4403 K (4130°C)
Density
22.56 g/cm³
Oxidation States
+3, +4
Electron Configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d⁷ 6s²
[Xe] 4f¹⁴ 5d⁷ 6s²
Shell 1:2e⁻
Shell 2:8e⁻
Shell 3:18e⁻
Shell 4:32e⁻
Shell 5:15e⁻
Shell 6:2e⁻
Real-World Uses
Spark plugs
Crucibles for high temperatures
Pen nibs
Compass bearings
International kilogram replica
Fun Fact
The asteroid that killed the dinosaurs left a thin layer of iridium in rock worldwide — it's how scientists pinpointed when the impact occurred!