Atomic Properties of Ir
- Atomic Number of Ir
- 77
- Atomic Mass of Ir
- 192.2200 u
- Electron Configuration
- [Xe] 4f14 5d7 6s2
- Electronegativity
- 2.20
- Block
- d-block
- Group
- 9
- Period
- 6
Iridium (Ir) is element 77 on the periodic table. Atomic mass of Ir: 192.2200 u. Ir is in period 6, group 9. Melting point of Ir: 2719.00 K.Density of Ir: 22.56 g/cm³.
Iridium in everyday life and industry
Iridium has no known biological role. Some iridium compounds are being researched for cancer treatment. Iridium is found in the K-Pg boundary layer linked to dinosaur extinction.
Discovered by S.Tenant, A.F.Fourcory, L.N.Vauquelin, H.V.Collet-Descoltils in England/France, 1804
Name origin: Latin: iris (rainbow).
The most corrosion-resistant metal known, attacked by no acid at any temperature. Second densest element after osmium at 22.56 g/cm3. Named for Greek goddess Iris (rainbow) because its salts display many colors. The famous K-Pg boundary iridium anomaly—a thin layer worldwide enriched 30× in iridium—provided key evidence for the asteroid impact that ended the dinosaurs 66 million years ago.
Iridium has 2 naturally occurring isotopes, plus 1 notable radioactive isotope.
| Isotope | Atomic Mass (u) | Abundance | Half-Life | Decay Mode |
|---|---|---|---|---|
| 19177Ir (Ir-191)Iridium-191 isotope | 190.9605893 | 37.30% | — | — |
| 19277Ir (Ir-192)Iridium-192 isotope | 191.9626 | 0% | 73.8 days | β⁻, EC, β⁺ |
| 19377Ir (Ir-193)Iridium-193 isotope | 192.9629216 | 62.70% | — | — |
Data source: NIH PubChem (aggregated from IUPAC, NIST)
Isotopes of Iridium have important real-world applications in science and industry.
Metallic 192Ir (with a half-life of 74 days) is used as a radiation source in gamma cameras for non-destructive testing of products for manufacturing flaws, such as aircraft parts, boilers, and pipeline welds (Fig. IUPAC.77.1) [274].
Metallic 192Ir is used in brachytherapy [188], [521], [522], [523]. 191mIr (with a half-life of 5 s) is used for blood flow imaging (angiography), especially in pediatric populations [524], [525]. The m in the superscript 191mIr indicates a metastable state of the isotope.
Used with osmium to tip gold pen points, to make crucible and special containers. Also to make alloys used for standard weights and measures, and heat-resistant alloys. Also as hardening agent for platinum.
Found in gravel deposits with platinum.
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