Iridium (Ir) — Element 77

77 Ir 192.22

Iridium

Element 77 · 192.22 u · d-block

transition metal

The most corrosion-resistant metal known. An iridium-rich layer in rock marks the asteroid impact that killed the dinosaurs.

Phase (STP)

Solid

Melting Point

2446 °C

Boiling Point

4428 °C

Density

22.56 g/cm³

Electronegativity

2.2

Atomic Radius

135 pm

Ionization Energy

880 kJ/mol

Electron Affinity

151 kJ/mol

Discovered

1803 · Smithson Tennant

Electron Configuration

[Xe] 4f14 5d7 6s2