Chemical element · Atomic number 77
Iridium
Iridium in the periodic table: atomic number 77, electron configuration, atomic mass, physical data, oxidation states, media credit and visible sources.
Transition metal
solid
192.22 u
Documented element sampleA documented sample of elemental iridium; the platinum group metal appears silvery-gray.
Image credit: James St. John
Auto-oriented, limited to 1600 × 1200 pixels and re-encoded as WebP; the subject was not altered.
Atomic classification
Shell occupancy
Iridium in the Bohr shell model
This shows the electron distribution of the neutral atom in a simplified shell model.
- K · n=1
- 2 electrons
- L · n=2
- 8 electrons
- M · n=3
- 18 electrons
- N · n=4
- 32 electrons
- O · n=5
- 15 electrons
- P · n=6
- 2 electrons
- Electron configuration
- [Xe]6s2 4f14 5d7
- Electrons per shell
- 2 · 8 · 18 · 32 · 15 · 2
- Group
- 9
- Period
- 6
- Block
- D
- Element category
- Transition metal
Physical and chemical properties
- Atomic mass
- 192.22 u
- Standard state
- solid
- Density
- 22.42 g/cm³
- Melting point
- 2,719 K
- Boiling point
- 4,701 K
- Electronegativity
- 2.2 (Pauling)
- First ionisation energy
- 9.1 eV
- Oxidation states
- +4, +3
- Discovery
- 1803
Safety and periodic classification
Safety
Safe handling cannot be inferred from Iridium's position in the periodic table alone. Laboratory, classroom and disposal decisions must follow the documentation for the exact material and its safety data sheet.
Position and comparison
Iridium is in period 6, group 9 and the D block. Its direct neighbours by atomic number are Osmium and Platinum. The recorded Pauling electronegativity is 2.2. Periodic trends are compared only through the separately sourced neighbouring values.
Sources and scope
PubChem attributes element data to sources including IUPAC, NIST and IAEA. Quanta stores the referenced snapshot locally and leaves unknown values unavailable.
Where Iridium sits among the 118 elements
The table compares the reported values for Iridium with every other element that carries the same value in the snapshot. A rank is not a judgement, it is orientation: it says how unusual this value is across the periodic table.
| Value | Iridium | Position in the data set |
|---|---|---|
| Melting point | 2,719 K | Rank 8 of 103 elements with a reported value. Highest: Carbon. |
| Boiling point | 4,701 K | Rank 9 of 93 elements with a reported value. Highest: Rhenium. |
| Density | 22.42 g/cm³ | Rank 2 of 96 elements with a reported value. Highest: Osmium. |
| Electronegativity (Pauling) | 2.2 | Rank 21 of 95 elements with a reported value. Highest: Fluorine. |
| Ionisation energy | 9.1 eV | Rank 24 of 102 elements with a reported value. Highest: Helium. |
All values and ranks come from the PubChem Periodic Table snapshot, retrieved on 2026-07-15. Elements without a reported value are excluded, so the population differs per row.
The neighbours of Iridium in the periodic table
- Place in the table
- Group 9, period 6, D block. Classified as transition metal, solid at standard conditions.
- Direct neighbours
- Atomic number 77. Preceded by Osmium, followed by Platinum.
- Same group
- Same number of outer electrons, and therefore similar reactivity to Cobalt, Rhodium, Meitnerium.
- Discovery
- Recorded in the snapshot as: 1803. Who, where and under what circumstances is not part of that record, so this page carries the sourced year and no discovery narrative.
- Oxidation states
- +4, +3. They follow from the electron configuration [Xe]6s2 4f14 5d7 and indicate which compounds to expect.
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