Iridium
Element 77 on the periodic table, symbol Ir, group 9, period 6.
Iridium is a chemical element with symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group, iridium is generally credited with being the second densest element (after osmium) based on measured density, although calculations involving the space lattices of the elements show that iridium is denser. It is also the most corrosion-resistant metal, even at temperatures as high as 2000 °C. Although only certain molten salts and halogens are corrosive to solid iridium, finely divided iridium dust is much more reactive and can be flammable.
Appearance: silvery white
Properties
- Atomic Number
- 77
- Atomic Mass
- 192.2173 u
- Group
- 9
- Period
- 6
- Block
- d-block
- Category
- Transition Metal
- State at 25 °C
- Solid
- Melting Point
- 2,719 K · 2,445.9 °C
- Boiling Point
- 4,403 K · 4,129.9 °C
- Density
- 22.56 g/cm³
- Atomic Radius
- 135 pm
- Electronegativity
- 2.2
- Oxidation States
- +3, +4
- Abundance in Crust
- 0.001 mg/kg
- Discovered
- 1803
- Discovered By
- Smithson Tennant
Electron Configuration
[Xe] 4f14 5d7 6s2
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d7
Ionisation Energies (kJ/mol)
- 1. 880
- 2. 1,600
Elements near Iridium
Elements in the same group share the number of outer electrons and behave in similar ways. Elements in the same period share a shell, so they change steadily from left to right.