I

Iridium

IUPAC: Iridium

Ir Elements CAS 7439-88-5
Quick Reference
Formula / NotationIr
CAS Number7439-88-5
Molecular Weight192.22
Melting Point2446.0
Boiling Point4428.0
Density22.56
SolubilityInsoluble in water
AppearanceHard, brittle, silvery-white metal
Also Known AsIr, iridium metal
CategoryElements

What is Iridium?

Iridium is a hard, brittle, silvery-white platinum group metal, atomic number 77. The most corrosion-resistant metal known. Second densest element after osmium. The Cretaceous-Paleogene (K-Pg) extinction event asteroid impact was identified by anomalous iridium layer in sediments.

Formula & Notation

Ir

IUPAC Name: Iridium

Other Names / Synonyms: Ir, iridium metal

Properties & Characteristics

Atomic number: 77. Atomic mass: 192.22 g/mol. Period 6, Group 9. Melting point: 2446 C. Boiling point: 4428 C. Density: 22.56 g/cm3. Electronegativity: 2.20. Oxidation states: +1, +3, +4. Two stable isotopes: Ir-191 (37.3%), Ir-193 (62.7%). Most corrosion resistant metal.

Physical Data

PropertyValue
Melting Point2446.0
Boiling Point4428.0
Density22.56
Molecular Weight192.22
SolubilityInsoluble in water
AppearanceHard, brittle, silvery-white metal

Uses & Applications

Iridium-platinum alloys for spark plug electrodes (long-life). International Prototype Kilogram (Pt-Ir alloy). Catalyst for acetic acid production (Monsanto and Cativa processes). Osmium-iridium alloy tips. Ir-192 industrial radiography source. Crucibles for extreme temperatures.

Safety Information

Iridium metal: low acute toxicity. Iridium compounds: moderate toxicity. Finely divided iridium dust: combustible. Ir-192: gamma-emitting industrial source - radiation hazard, strict regulatory control. IrCl3 and other compounds: irritant.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Iridium
Formula Ir
CAS Number 7439-88-5
Molecular Weight 192.22
Category Elements
Synonyms Ir, iridium metal

Frequently Asked Questions

Iridium is a hard, brittle, silvery-white platinum group metal, atomic number 77. The most corrosion-resistant metal known. Second densest element after osmium. The Cretaceous-Paleogene (K-Pg) extinction event asteroid impact was identified by anomalous iridium layer in sediments.

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