77192.22IrIridium
Iridium (Ir) — element 77transition metal · group 9, period 6
Iridium is a chemical element with the symbol Ir and atomic number 77. It is a transition metal in group 9, period 6 of the periodic table (the d-block), with a standard atomic mass of 192.22 u. At room temperature (25 °C) iridium is a solid.
💡 Known for: The most corrosion-resistant metal; an iridium-rich clay layer marks the asteroid impact that ended the dinosaurs.
# Iridium properties
| Symbol | Ir |
|---|---|
| Atomic number | 77 |
| Atomic mass | 192.22 u |
| Category | transition metal |
| Group | 9 |
| Period | 6 |
| Block | d-block |
| Electron configuration | [Xe] 4f¹⁴ 5d⁷ 6s² |
| Full configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d⁷ 6s² |
| Electrons per shell | 2, 8, 18, 32, 15, 2 |
| Protons / electrons | 77 / 77 |
| State at 25 °C | solid |
| Melting point | 2719 K (2445.8 °C, 4434.5 °F) |
| Boiling point | 4701 K (4427.9 °C, 8002.1 °F) |
| Density | 22.56 g/cm³ |
| Electronegativity (Pauling) | 2.2 |
| First ionization energy | 8.967 eV |
| Atomic radius | 180 pm |
| Discovered | 1803 |
# Electron configuration of iridium
The electron configuration of iridium is [Xe] 4f¹⁴ 5d⁷ 6s², written out in full as 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d⁷ 6s². Its 77 electrons fill 6 shells as 2, 8, 18, 32, 15, 2, so the outermost shell holds 2 electrons.
# Related elements
OsOsmiumprevious elementPtPlatinumnext elementCoCobaltgroup 9RhRhodiumgroup 9MtMeitneriumgroup 9ScScandiumtransition metalTiTitaniumtransition metalVVanadiumtransition metalCrChromiumtransition metalMnManganesetransition metalFeIrontransition metalNiNickeltransition metalCuCoppertransition metal
# Iridium FAQ
What is the atomic number of iridium?
The atomic number of iridium is 77: every iridium atom has 77 protons in its nucleus. Its symbol is Ir.
What is the atomic mass of iridium?
The standard atomic mass of iridium is 192.22 u.
What is the electron configuration of iridium?
Iridium's electron configuration is [Xe] 4f¹⁴ 5d⁷ 6s² (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d⁷ 6s²), with 2, 8, 18, 32, 15, 2 electrons per shell.
Is iridium a metal?
Yes. Iridium is a transition metal, one of the metals.
What is the melting point of iridium?
Iridium melts at 2719 K (2445.8 °C, 4434.5 °F) and boils at 4701 K (4427.9 °C, 8002.1 °F).
What is iridium used for / known for?
The most corrosion-resistant metal; an iridium-rich clay layer marks the asteroid impact that ended the dinosaurs.