Element Iridium

Iridium ElementIt is an element with atomic symbol Ir, atomic number 77, and atomic weight 192.217.
A very hard, brittle, silvery-white transition metal of the platinum group, iridium is the second-densest metal (after osmium) with a density of 22.56 g/cm³ as defined by experimental X-ray crystallography.
The most important iridium compounds in use are the salts and acids it forms with chlorine, though iridium also forms a number of organometallic compounds used in industrial catalysis, and in research.
Iridium metal is employed when high corrosion resistance at high temperatures is needed, as in high-performance spark plugs, crucibles for recrystallization of semiconductors at high temperatures, and electrodes for the production of chlorine in the chloralkali process. Element Iridium radioisotopes are used in some radioisotope thermoelectric generators.

Names and Identifiers

Chemical Formula:Ir
CAS:7439-88-5
Molecular Weight:192.21700g/mol
EC Number :231-095-9
MDL Number:MFCD00011062
Color:silvery white/ silvery-white
Other Names:Iridio
PubChem CID:23924
IUPAC Name:Iridium
Inchl:InChI=1S/Ir
InChI Key:GKOZUEZYRPOHIO-UHFFFAOYSA-N
Canonical SMILES:[Ir]
ICSC Number:n/a

Physical & Chemical Properties

Phase:Solid
Density:22.56 g/cm³
Boiling Point:4403 K ​(4130 °C, ​7466 °F)
Melting Point:32719 K ​(2446 °C, ​4435 °F)
Molecular Formula:Ir
Flash Point:n/a
Exact Mass:192.96300
Symbol:Globally Harmonized System of ClassificationGlobally Harmonized System of Classification
Signal Word:Danger
Hazard Statements:H228-H319
Precautionary Statements:P210-P305 + P351 + P338
Hazard Codes:Xi:Irritant
Risk Phrases:R36/37/38
Safety Phrases:S16-S26-S36/37/39
RIDADR:UN 3089 4.1/PG 2
WGK Germany:3
RTECS:n/a
Packaging Group:III
Hazard Class:4.1

Iridium has two naturally occurring, stable isotopes, 191Ir and 193Ir, with natural abundances of 37.3% and 62.7%, respectively.
At least 37 radioisotopes have also been synthesized, ranging in mass number from 164 to 202. 192Ir, which falls between the two stable isotopes, is the most stable radioisotope, with a half-life of 73.827 days.

Naturally occurring isotopes

IsotopeMass/DaNatural abundance (atom %)Nuclear spin (I)Magnetic moment (μ/μN)
191Ir190.960584 (4)37.3 (2)3/20.1462
193Ir192.962917 (4)62.7 (2)3/20.1592

Radiosotope data

IsotopeMass/DaHalf-lifeMode of decayNuclear spinNuclear magnetic moment
188Ir187.958851.72 dEC to 188Os20.30
189Ir188.9587213.2 dEC to 189Os3/20.13
190Ir189.960611.8 dEC to 190Os40.04
192Ir191.96260273.83 dβ to 192Pt41.92

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