Iridium Elemental Symbol

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Iridium Iridium Iridio Irídio Irídio Iridium

Iridium(Ir) atomic and molecular weight, atomic number and elemental symbolIridium is a Block D, Group 9, Period 6 element. The number of electrons in each of iridium's shells is 2, 8, 18, 32, 15, 2 and its electron configuration is [Xe] 4f14 5d7 6s2. Elemental IridiumThe iridium atom has a radius of and its Van der Waals radius is Iridium Bohr ModelIn its elemental form, CAS 7439-88-5, Iridium has a silvery white appearance. Iridium is a member of the platinum group of metals. It is the most corrosion resistant metal known and is the second-densest element (after osmium). It will not react with any acid and can only be attacked by certain molten salts, such as molten sodium chloride. Iridium is found as an uncombined element and in iridium-osmium alloys. Iridium was first discovered by Smithson Tennant in 1803. Iridium's name is derived from the Greek goddess Iris, personification of the rainbow, on account of the striking and diverse colors of its salts.

Iridium is alloyed with platinum to produce highly corrosion resistant electrical contacts for spark plugs. High Purity (99.999%) Iridium Oxide (IrO2) PowderIridium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity). High Purity (99.999%) Iridium (Ir)Sputtering TargetElemental or metallic forms include pellets, rod, wire and granules for evaporation source material purposes. Iridium nanoparticles and nanopowders provide ultra-high surface area which nanotechnology research and recent experiments demonstrate function to create new and unique properties and benefits. Oxides are available in powder and dense pellet form for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Fluorides are another insoluble form for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Iridium is also available in soluble forms including chlorides, nitrates and acetates. These compounds can be manufactured as solutions at specified stoichiometries.

Iridium is only slightly toxic in its elemental form; however, safety data for Iridium and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the Products tab below.

  • Properties
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  • Isotopes
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Iridium Properties

Symbol: Ir Melting Point: 2739 K, 2466 °C, 4471 °F
Atomic Number: 77 Boiling Point: 4701 K, 4428 °C, 8002 °F
Atomic Weight: 192.217 Density: 22.56 g·cm−3
Element Category: transition metal Liquid Density @ Melting Point: 19 g·cm−3
Group, Period, Block: 9, 6, d Specific Heat: 0.13 (kJ/kg K)
    Heat of Vaporization 612.1 kJ mol-1
CHEMICAL STRUCTURE Heat of Fusion 26.4 kJ mol-1
Electrons: 77 Thermal Conductivity: 147 W·m−1·K−1
Protons: 77 Thermal Expansion: 6.4 µm/(m·K)
Neutrons: 115 Electrical Resistivity: (20 °C) 47.1 nΩ·m
Electron Configuration: [Xe] 4f145d76s2 Electronegativity: 2.20 (Pauling scale)
Atomic Radius: Tensile Strength: N/A
Covalent Radius: 141± Molar Heat Capacity: 25.10 J·mol−1·K−1
Van der Waals radius: Young's Modulus: 528 GPa
Oxidation States: −3,−1, 0, 1, 2, 3, 4, 5, 6 Shear Modulus: 210 GPa
Phase: Solid Bulk Modulus: 320 GPa
Crystal Structure: face-centered cubic Poisson Ratio: 0.26
Magnetic Ordering: paramagnetic Mohs Hardness: 6.5
1st Ionization Energy: 880 kJ·mol−1 Vickers Hardness: 1760 MPa
2nd Ionization Energy: 1600 kJ·mol−1 Brinell Hardness: 1670 MPa
3rd Ionization Energy: N/A Speed of Sound: (20 °C) 4825 m·s−1
CAS Number: 7439-88-5 Abundance in typical human body, by weight: N/A
ChemSpider ID: 22367 Abundance in typical human body, by atom: N/A
PubChem CID: 23924 Abundance in universe, by weight: 2 ppb
MDL Number: MFCD00011062 Abundance in universe, by atom: 0.01 ppb
EC Number: 231-095-9 Discovered By: Smithson Tennant
Beilstein Number: N/A Discovery Date: 1803
SMILES Identifier: [Ir]  
InChI Identifier: InChI=1S/Ir Other Names: Iridio

Iridium Products

Metal Forms  •  Compounds  •  Alloys  •  Oxide Forms  •  Organometallic Compounds
Sputtering Targets  •  Nanomaterials  •  Semiconductor Materials •  Isotopes

Organometallic Compounds

(1,5-Cyclooctadiene)(methoxy)iridium(I) Dimer



(2,4-Pentanedionato-O2,O4)bis[2-(1H -pyrazol-1-yl-N2)phenyl

Bis(1,5-cyclooctadiene)diiridium(I) dichloride
Bis(1,5-cyclooctadiene)iridium(I) Tetrafluoroborate
Bis[1,2-bis(diphenylphosphino) ethane]carbonyl chloroiridium(I)
Bis(cyclooctadiene)iridium(I) tetrakis(3,5-bis(trifluoromethyl)phenyl)borate
Carbonylchlorobis(triphenylphosphine) iridium(I)
Carbonylhydridotris (triphenylphosphine)iridium(I)
Chloro(1,5-cyclooctadiene)iridium(I) Dimer
Chlorodihydrido[bis(2-diisopropylphosphino)ethylamine]iridium(III), Mixture of Isomers
Diiodo(pentamethylcyclopentadienyl)iridium(III) dimer
Iridium Acetylacetonate
Iridium(IV) Chloride Hydrate
Iridium 2 - Ethylhexanoate
Iridium(I) Hexafluorophosphate
Iridium(IV) Oxide Hydrate
Iridium(III) 2,4-pentanedionate
Iridium Trifluoromethanesulfonate
Pentaamminechloroiridium(III) Chloride
Pentamethylcyclopentadienyliridium(III) Chloride, dimer

Crystal/ Semiconductor Materials

Iridium Phosphide
Iridium Selenide
Iridium Silicide
Iridium Sulfide
Iridium Telluride


Iridium Manganese
Platinum Iridium Alloy
Platinum/Iridium Foil
Platinum/Iridium Tube
Platinum/Iridium Wire

Recent Research & Development for Iridium

  • Yi-Ting Shih, Kuei-Yi Lee, Ying-Sheng Huang, Characterization of iridium dioxide–carbon nanotube nanocomposites grown onto graphene for supercapacitor, Journal of Alloys and Compounds, Volume 619, 15 January 2015
  • Tongtong Li, Malin Cui, Guoxia Ran, Qijun Song, Ionic iridium complexes with conjugated phenyl substituent: Synthesis and DFT calculation on the electrochemical and electrochemiluminescent properties, Dyes and Pigments, Volume 112, January 2015
  • Hong-Tao Cao, Guo-Gang Shan, Yong-Ming Yin, Hai-Zhu Sun, Yong Wu, Wen-Fa Xie, Zhong-Min Su, Modification of iridium(III) complexes for fabrication of high-performance non-doped organic light-emitting diode, Dyes and Pigments, Volume 112, January 2015
  • Xiaoting Chen, Conghui Si, Yulai Gao, Jan Frenzel, Junzhe Sun, Gunther Eggeler, Zhonghua Zhang, Multi-component nanoporous platinum–ruthenium–copper–osmium–iridium alloy with enhanced electrocatalytic activity towards methanol oxidation and oxygen reduction, Journal of Power Sources, Volume 273, 1 January 2015
  • Cigdem Sahin, Aysen Goren, Canan Varlikli, Synthesis, characterization and photophysical properties of iridium complexes with amidinate ligands, Journal of Organometallic Chemistry, Volumes 772–773, 1 December 2014
  • Yige Qi, Xu Wang, Ming Li, Zhiyun Lu, Junsheng Yu, Highly efficient and concentration-insensitive organic light-emitting devices based on self-quenching-resistant orange–red iridium complex, Journal of Luminescence, Volume 155, November 2014
  • Shigeru Ikawa, Shigeyuki Yagi, Takeshi Maeda, Hiroyuki Nakazumi, Yoshiaki Sakurai, White polymer light-emitting diodes co-doped with three phosphorescent iridium(III) complexes aimed at improvement of color rendering properties, Journal of Luminescence, Volume 155, November 2014
  • Sule Erten-Ela, Kasim Ocakoglu, Iridium dimer complex for dye sensitized solar cells using electrolyte combinations with different ionic liquids, Materials Science in Semiconductor Processing, Volume 27, November 2014
  • Keqi He, Xiangdong Wang, Junting Yu, Haigang Jiang, Guangshan Xie, Hua Tan, Yu Liu, Dongge Ma, Yafei Wang, Weiguo Zhu, Synthesis and optoelectronic properties of novel fluorene-bridged dinuclear cyclometalated iridium (III) complex with A–D–A framework in the single-emissive-layer WOLEDs, Organic Electronics, Volume 15, Issue 11, November 2014
  • Li-Yuan Guo, Xun-Lu Zhang, Min-Jie Zhuo, Chen Liu, Wang-Yang Chen, Bao-Xiu Mi, Juan Song, Yong-Hua Li, Zhi-Qiang Gao, Non-interlayer and color stable WOLEDs with mixed host and incorporating a new orange phosphorescent iridium complex, Organic Electronics, Volume 15, Issue 11, November 2014

Iridium Isotopes

There are two natural isotopes of iridium (Ir): 191Ir and 193Ir.

Nuclide Symbol Isotopic Mass Half-Life Nuclear Spin
191Ir 190.9605940 Observationally Stable 3/2+
193Ir 192.9629264 Observationally Stable 3/2+