Iridium (Ir)

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 the second-densest element (after osmium).

Atomic Number

77

Atomic Mass

192.22 u

Category

transition metal

Phase

solid

Density

22.56 g/cm³

Electron Shells

2, 8, 18, 32, 15, 2

Atomic Structure

Protons: 77 • Electrons: 77 • Neutrons: Varies by isotope

Electron Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d⁷

Discovery

1803 • Smithson Tennant