Ir
Iridium
Element 77 · Transition metal
Iridium (Ir)
Iridium is the most corrosion-resistant metal known. It is extremely dense, hard and rare.
- Transition metal
- Period 6
- Group 9
- d-block
- solid at room temperature
Key properties
- Atomic mass
- 192.22
- u
- Electron configuration
- [Xe] 4f14 5d7 6s2
- Melting point
- 2,445.9 °C
- 2,719 K
- Boiling point
- 4,427.9 °C
- 4,701 K
- Density
- 22.42 g/cm³
- Electronegativity
- 2.2
- Pauling
- Atomic radius
- 202 pm
- van der Waals
- 1st ionisation energy
- 9.1 eV
Compare with every element:Electronegativity chartAtomic radius chartIonisation energy chartDensity chart of the elementsMelting point chartElectron configuration chart
Did you know?
Notable facts about iridium
- 01
A worldwide layer of iridium-rich clay marks the asteroid impact that ended the age of dinosaurs.
- 02
The international prototype metre and kilogram were made of platinum–iridium.
- 03
Iridium is used in spark plugs that last over 100,000 miles.
Applications
What is iridium used for?
- Spark plugs
- Crucibles for crystal growth
- Electrodes
- Fountain-pen nibs
History
Discovery & name origin
Discovered by
Year
Where
England
Name origin
Greek iris, “rainbow”, for its many-coloured salts.
Atomic structure
Atomic properties
Atomic structure
Atomic properties
- Atomic number
- 77
- Atomic mass
- 192.22 u
- Group
- 9
- Period
- 6
- Block
- d-block
- Electron configuration
- [Xe] 4f14 5d7 6s2
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d7
- Electrons per shell
- 2, 8, 18, 32, 15, 2
- Electronegativity (Pauling)
- 2.2
- Electron affinity
- 1.565 eV
- Atomic radius (van der Waals)
- 202 pm
- Stable isotopes
- 2
Oxidation states
Highlighted: common oxidation states (+4, +3).
Successive ionisation energies
Energy to remove each electron in turn (kJ/mol). Big jumps show where a new, inner shell begins.
- 1st880
- 2nd1,600
Physical
Physical properties & colour
Physical
Physical properties & colour
- State at 20 °C
- Solid
- Melting point
- 2,719 K · 2,445.9 °C · 4,434.5 °F
- Boiling point
- 4,701 K · 4,427.9 °C · 8,002.1 °F
- Density
- 22.42 g/cm³
- Molar heat capacity
- 25.1 J/(mol·K)
- Appearance
- Silvery white
- CPK model colour
- Copied
The CPK colour is the convention used for this element’s atoms in molecular models.
FAQ
Iridium questions
What is Ir on the periodic table?
Ir is the symbol for iridium, element 77 on the periodic table. It sits in group 9, period 6, in the transition metal category, and has an atomic mass of 192.22.
What is the atomic number of iridium?
Iridium has atomic number 77, so every iridium atom has 77 protons in its nucleus. Its symbol is Ir and its atomic mass is 192.22.
Who discovered iridium?
Iridium was discovered by Smithson Tennant in 1803 (England). The name comes from Greek iris, “rainbow”, for its many-coloured salts.
What is iridium used for?
Iridium is used for: spark plugs; crucibles for crystal growth; electrodes; fountain-pen nibs.
Is iridium a metal?
Yes. Iridium is a transition metal, one of the metallic elements.
What is the electron configuration of iridium?
The electron configuration of iridium is [Xe] 4f14 5d7 6s2. Its 77 electrons are arranged in shells as 2, 8, 18, 32, 15, 2.