Iridium (Ir)
transition-metalSolid
標準原子量
192.217 u電子配置
[Xe] 6s2 4f14 5d7融点
2445.85 °C沸点
4427.85 °C密度
2.25622e+4 kg/m³酸化数
−3, −2, −1, +1, +2, +3, +4, +5, +6, +7, +8, +9電気陰性度（Pauling）
2.2第1イオン化エネルギー
8.96702 eV発見年
1803原子半径
135 pm詳細
Iridium is a very dense platinum-group transition metal with exceptional resistance to corrosion and high-temperature attack. It occurs naturally mainly with platinum-group minerals and in nickel-copper sulfide ores. Chemically it forms robust complexes, especially in oxidation states +3 and +4, and it is notable for the global iridium anomaly associated with the Cretaceous-Paleogene boundary impact layer.
Iridium, a metal of the platinum family, is white (similar to platinum) but with a slight yellowish cast. Because iridium is very hard and brittle, it is hard to machine, form, or work.
It is the most corrosion-resistant metal known, and was used in making the standard meter bar of Paris, which is a 90 percent platinum and 10 percent iridium alloy. This meter bar was replaced in 1960 as a fundamental unit of length (see Krypton).
Iridium is not attacked by any of the acids nor by aqua regia, but is attacked by molten salts, such as NaCl and NaCN. The specific gravity of iridium is to osmium's specific gravity. Calculations of the densities of iridium and osmium from the space lattices give values of 22.65 and 22.61 g/cm^3, respectively. These values may be more reliable than actual physical measurements for determining which element is heavier.
The name derives from the Latin Iris, the Greek goddess of rainbows, because of the variety of colours in the element's salt solutions. Iridium and osmium were both discovered in a crude platinum ore in 1803 by the English chemist Smithson Tennant. Iridium was discovered independently by the French chemist H. V. Collet-Descotils, who actually published his paper one month before Tennant, but Tennant is given credit for the discovery, perhaps because he alone also found osmium in the ore.
Iridium and osmium were discovered at the same time by the British chemist Smithson Tennant in 1803. Iridium and osmium were identified in the black residue remaining after dissolving platinum ore with aqua regia, a mixture of 25% nitric acid (HNO3) and 75% hydrochloric acid (HCl). Today, iridium is still obtained from platinum ores and as a by-product of mining nickel.
From the Latin word iris meaning rainbow. Tennant discovered iridium in 1803 in the residue left when crude platinum is dissolved by aqua regia. The name iridium is appropriate because its salts are highly colored.
Pure iridium is a hard, brittle, silvery-white metal with a high luster. It remains bright in air under ordinary conditions and has an unusually high melting point. Bulk metal is difficult to machine because of its hardness and brittleness.
Iridium is used where chemical durability and high-temperature strength justify its cost. Major applications include crucibles for growing oxide crystals, spark-plug electrodes, electrical contacts, and wear-resistant alloys with platinum or osmium. Iridium coatings and components are used in some aerospace and industrial equipment. Radioisotope thermoelectric generators have used ¹⁹²Ir? No; ¹⁹²Ir is chiefly a gamma source for industrial radiography and some brachytherapy, not an energy source.
Pure iridium is very brittle and is nearly impossible to machine. It is primarily used as a hardening agent for platinum. Platinum-iridium alloys are used to make crucibles and other high temperature equipment. Iridium is also alloyed with osmium to make the tips of fountain pens and compass bearings.
Iridium is the most corrosive resistant metal known. For this reason, the standard meter bar was created from an alloy of 90% platinum and 10% iridium. This bar was replaced as the definition of the meter in 1960 when the meter was redefined in terms of the orange-red spectral line of krypton-86.
A thin, worldwide layer of iridium exists in a layer of sediment that was put down at the end of the Cretaceous period. Since meteors and asteroids contain a higher percentage of iridium than the earth's crust, this iridium enriched layer is seen as evidence that the earth was struck by a large meteor or asteroid at that time. Dust from the impact would have spread around the globe, depositing the iridium. The dust also would have blocked the sun for a time, resulting in the extinction of many plant and animal species, including the dinosaurs.
Although its principal use is as a hardening agent for platinum, iridium is also used to make crucibles and devices requiring high temperatures. It is also used for electrical contacts.
The element forms an alloy with osmium which is used for tipping pens and compass bearings.
Isotopes in 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] P. Hayward, D. Currie. “Radiography of welds using seleniuim 75, Ir 192 and x-rays”, in Asia-Pacific Conference on NDT, Auckland, New Zealand (2006)..
Isotopes in Medicine
Metallic 192Ir is used in brachytherapy [188] S. J. Adelstein, F. J. Manning. Isotopes for Medicine and the Life Sciences, pp. 20–25, National Academy Press, Washington DC (1995)., [521] A. Talamo, Y. Gohar. Radioactive Isotope Production for Medical Applications Using Kharkov Electron Driven Subcritical Assembly Facility, ANL-07/18, Argonne National Laboratory Argonne, Illinois (2007)., [522] S. A. Buzdar, M. A. Gadhi, M. A. Rao, N. A. Laghari, M. Anees. J. Pak. Med. Assoc.59, 113 (2009)., [523] T. Genkaa, S. Iwamotoa, E. Juitab, N. Takeuchia. Nucl. Inst. Methods Phys. Res. Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.369, 709 (1996).. 191mIr (with a half-life of 5 s) is used for blood flow imaging (angiography), especially in pediatric populations [524] K. J. Kairemo, M. S. Kestilä, S. Savolainen, O. A. Korhola, J. V. Hiltunen, R. I. Svahn, E. T. Korppi Tommola, F. F. Knapp, C. Brihaye. J. Nucl. Biol. Med.38, 86 (1994)., [525] S. T. Treves, A. B. Packard, L. C. T. Fung. J. Nucl. Med.45, 508 (2004).. The m in the superscript 191mIr indicates a metastable state of the isotope.
Isotopes Used as a Source of Radioactive Isotope(s)
Iridium consists of two stable isotopes (191Ir and 193Ir) from which the radioactive isotopes 192Ir and 195mPt (with a half-life of 4 days) can be produced. Both are used in nuclear medicine. The m in the superscript 195mPt indicates a metastable state of the isotope.
Iridium chemistry is dominated by coordination compounds and oxides rather than simple salts. Common oxidation states are +3 and +4, while lower and higher states occur in organometallic or strongly oxidizing systems. Iridium(IV) oxide, IrO₂, is an electrically conducting oxide used in dimensionally stable anodes and electrochemical research. Hexachloroiridic acid, H₂IrCl₆, and related chloroiridate salts are important refining and precursor compounds. The complex [Ir(ppy)₃] is a representative phosphorescent organoiridium emitter.
See more information at the Iridium compound page.
Massive iridium metal is chemically inert and has low acute toxicity, but finely divided powder can present dust and fire hazards. Soluble iridium salts and organoiridium compounds should be treated as potentially toxic because biological effects are compound-specific and incompletely characterized. The radionuclide ¹⁹²Ir emits penetrating gamma radiation and requires strict shielding and source control.
Iridium is extremely scarce in the crust and is usually dispersed with other platinum-group elements. Natural mobility is low because the metal and many of its minerals are resistant to weathering, although complexing ligands and industrial processing can mobilize small amounts. The sharp enrichment of iridium in some boundary clays is widely used as evidence for extraterrestrial material mixed into sediment.
Iridium is recovered chiefly as a by-product of platinum-group metal refining from nickel-copper sulfide ores and platinum placers. Supply is constrained by the production of the host metals, complex separation chemistry, and limited primary deposits. Demand is small but specialized, so substitution is possible in some electrical and catalytic uses but difficult in high-temperature crucibles and certain corrosion-resistant components. Recycling from spent electrodes, crucibles, and industrial scrap is important because the metal is rare and costly to replace.
Iridium occurs uncombined in nature with platinum and other metals of this family in alluvial deposits. It is recovered as a by-product from the nickel mining industry.
Iridium is a heavy r-process and s-process element made in late stellar evolution and explosive astrophysical environments. In the Solar System it is far more abundant in primitive meteorites than in Earth’s crust, because much of Earth’s original inventory partitioned into the core during differentiation. This siderophile behavior makes iridium a sensitive tracer of meteoritic input.
- Iridium is one of the densest elements, close to osmium in measured density.
- The name comes from Iris, reflecting the varied colors of some iridium salts.
- Iridium metal resists attack by aqua regia better than most noble metals.
- The Cretaceous-Paleogene boundary layer is enriched in iridium relative to ordinary crustal rocks.
- Iridium crucibles are used to grow some high-melting oxide crystals.
- Natural iridium consists mainly of the stable isotopes ¹⁹¹Ir and ¹⁹³Ir.
画像
性質
物理的性質
- 原子半径（経験値）
- 135 pm 全元素の原子半径（経験値）を比較 →
- 共有結合半径
- 141 pm 全元素の共有結合半径を比較 →
- ファンデルワールス半径
- 202 pm 全元素のファンデルワールス半径を比較 →
- 金属半径
- 127 pm 全元素の金属半径を比較 →
- 密度
- 2.25622 × 104 kg/m³ 全元素の密度を比較 →
- モル体積
- 0.00854 L/mol
- 標準温度・圧力（STP）での相
- 固体 全元素の標準温度・圧力（STP）での相を比較 →
- 融点
- 2445.85 °C 全元素の融点を比較 →
- 沸点
- 4427.85 °C 全元素の沸点を比較 →
- 熱伝導率
- 147 W/(m·K) 全元素の熱伝導率を比較 →
- 比熱容量
- 0.131 J/(g·K) 全元素の比熱容量を比較 →
- モル熱容量
- 25.1 J/(mol·K) 全元素のモル熱容量を比較 →
- 結晶構造
- 面心立方構造 全元素の結晶構造を比較 →
化学的性質
- 電気陰性度（Pauling）
- 2.2 全元素の電気陰性度（Pauling）を比較 →
- 電気陰性度（Allen）
- 1.68
- 電子親和力
- 1.565 eV
- 第1イオン化エネルギー
- 8.96702 eV 全元素の第1イオン化エネルギーを比較 →
- 第2イオン化エネルギー
- 17.000059 eV 全元素の第2イオン化エネルギーを比較 →
- 第3イオン化エネルギー
- 28.000096 eV 全元素の第3イオン化エネルギーを比較 →
- 第4イオン化エネルギー
- 40.000138 eV 全元素の第4イオン化エネルギーを比較 →
- 第5イオン化エネルギー
- 57.000196 eV 全元素の第5イオン化エネルギーを比較 →
- 酸化数
- −3, −2, −1, +1, +2, +3, +4, +5, +6, +7, +8, +9 全元素の酸化数を比較 →
- 価電子
- 9 全元素の価電子を比較 →
- 電子配置
- [Xe] 6s2 4f14 5d7
熱力学的性質
- 融解熱
- 0.27050837 eV 全元素の融解熱を比較 →
- 蒸発熱
- 6.26004 eV 全元素の蒸発熱を比較 →
- 昇華熱
- 6.944085 eV
- 原子化熱
- 6.944085 eV
- 原子化エンタルピー
- 6.93372 eV
原子核
- 陽子数
- 77 全元素の陽子数を比較 →
- 中性子数
- 116 全元素の中性子数を比較 →
- 既知の同位体
- 43 全元素の既知の同位体を比較 →
- 安定同位体
- 2 全元素の安定同位体を比較 →
- 最も安定な同位体
- Ir-193
- 発見年
- 1803
存在度
- 存在度（地殻）
- 0.001 mg/kg 全元素の存在度（地殻）を比較 →
結晶構造
- 格子定数a
- 384 pm
電子構造
- 各電子殻の電子数
- 2, 8, 18, 32, 15, 2 全元素の各電子殻の電子数を比較 →
識別子
- CAS登録番号
- 7439-88-5 全元素のCAS登録番号を比較 →
- 項記号
- 4F9/2
- InChI
- InChI=1S/Ir
- InChI Key
- GKOZUEZYRPOHIO-UHFFFAOYSA-N
電子配置 測定値
Ir: 4f¹⁴ 5d⁷ 6s²[Xe] 4f¹⁴ 5d⁷ 6s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d⁷ 6s²原子モデル
同位体によって中性子数、質量、安定性は変わりますが、中性原子の電子配置は変わりません。
模式的な原子モデルです。実際の縮尺とは異なります。
原子の指紋
発光／吸収スペクトル
同位体分布
| 質量数 | 原子質量（u） | 天然存在比 | 半減期 |
|---|---|---|---|
| 191 安定 | 190.9605893 ± 0.0000021 | 37.3000% | 安定 |
| 193 安定 | 192.9629216 ± 0.0000021 | 62.7000% | 安定 |
相／状態
理由: 融点（2445.85 °C）より2420.8 °C低い
模式図、実際の縮尺とは異なります
相転移点
相転移エネルギー
融点で1 molを融解させるのに必要なエネルギー
沸点で1 molを蒸発させるのに必要なエネルギー
昇華点で1 molを昇華させるのに必要なエネルギー
密度
標準条件下
標準条件下
原子スペクトル
全77件中10件を表示しています。 イオンの電荷の昇順で並べています。
スペクトル線データの収録状況 ?
| イオン | 電荷 | スペクトル線の総数 | 遷移確率 | 準位の表記 |
|---|---|---|---|---|
| Ir I | 0 | 402 | 70 | 398 |
| Ir II | +1 | 473 | 129 | 473 |
| Ir IV | +3 | 1374 | 1374 | 1374 |
準位データの収録状況 ?
| イオン | 電荷 | 準位 |
|---|---|---|
| Ir I | 0 | 231 |
| Ir II | +1 | 76 |
| Ir III | +2 | 2 |
| Ir IV | +3 | 224 |
| Ir V | +4 | 2 |
| Ir VI | +5 | 2 |
| Ir VII | +6 | 2 |
| Ir VIII | +7 | 2 |
| Ir IX | +8 | 2 |
| Ir X | +9 | 2 |
イオン半径
| 電荷 | 配位 | スピン | 半径 |
|---|---|---|---|
| +3 | 6 | データなし | 68 pm |
| +4 | 6 | データなし | 62.5 pm |
| +5 | 6 | データなし | 56.99999999999999 pm |
化合物
同位体 (2)
| 質量数 | 原子質量（u） | 天然存在比 | 半減期 | 崩壊形式 | |
|---|---|---|---|---|---|
| 191 安定 | 190.9605893 ± 0.0000021 | 37.3000% ± 0.2000% | 安定 | stable | |
| 193 安定 | 192.9629216 ± 0.0000021 | 62.7000% ± 0.2000% | 安定 | stable |
スペクトル線
| 波長（nm） | 強度 | 電離段階 | 種類 | 遷移 | 精度 | 出典 | |
|---|---|---|---|---|---|---|---|
| 382.7577 nm | 58 | Ir II | emission | 5d7.(2D2).6s 3D → 5d7.(4F<5/2>).6p (5/2,1/2)* | 測定値 | NIST | |
| 384.593 nm | データなし | Ir II | emission | 5d7.(2G).6s 1G → 5d7.(4F<9/2>).6p (9/2,3/2)* | 測定値 | NIST | |
| 387.3624 nm | 9 | Ir II | emission | 5d6.6s2 5D → 5d7.(4P<5/2>).6p (5/2,1/2)* | 測定値 | NIST | |
| 389.558 nm | データなし | Ir II | emission | 5d6.6s2 5D → 5d7.(4F<7/2>).6p (7/2,1/2)* | 測定値 | NIST | |
| 395.1973 nm | データなし | Ir II | emission | 5d6.6s2 5D → 5d7.(4F<9/2>).6p (9/2,1/2)* | 測定値 | NIST | |
| 395.2882 nm | 8 | Ir II | emission | 5d7.(2H).6s 3H → 5d6.6s.(6D<9/2>).6p (9/2,1/2)* | 測定値 | NIST | |
| 397.882 nm | 6 | Ir II | emission | 5d7.(2F).6s 3F → 5664* | 測定値 | NIST | |
| 398.6377 nm | 5 | Ir II | emission | 5d6.6s2 5D → 5d7.(4F<3/2>).6p (3/2,1/2)* | 測定値 | NIST | |
| 399.0389 nm | 6 | Ir II | emission | 5d6.6s2 3H → 6197* | 測定値 | NIST | |
| 400.1961 nm | 12 | Ir II | emission | 5d7.(2D2).6s 3D → 5d7.(4P<5/2>).6p (5/2,1/2)* | 測定値 | NIST | |
| 402.5321 nm | 4 | Ir II | emission | 5d7.(2F).6s 3F → 5d6.6s.(6D<5/2>).6p (5/2,1/2)* | 測定値 | NIST | |
| 402.5399 nm | 29 | Ir II | emission | 5d7.(2D2).6s 3D → 5d7.(4F<7/2>).6p (7/2,1/2)* | 測定値 | NIST | |
| 404.1381 nm | 45 | Ir II | emission | 5d7.(2H).6s 3H → 5d7.(4F<9/2>).6p (9/2,1/2)* | 測定値 | NIST | |
| 404.4911 nm | 7 | Ir II | emission | 5d7.(2F).6s 3F → 5d7.(4F<9/2>).6p (9/2,3/2)* | 測定値 | NIST | |
| 410.8315 nm | 48 | Ir II | emission | 5d7.(2F).6s 3F → 5d7.(4F<5/2>).6p (5/2,1/2)* | 測定値 | NIST | |
| 411.7209 nm | 3 | Ir II | emission | 5d7.(2G).6s 3G → 5d7.(4F<9/2>).6p (9/2,1/2)* | 測定値 | NIST | |
| 412.8911 nm | 17 | Ir II | emission | 5d7.(2P).6s 3P → 5d7.(4P<1/2>).6p (1/2,1/2)* | 測定値 | NIST | |
| 413.91 nm | 21 | Ir II | emission | 5d7.(2P).6s 3P → 5d7.(4F<9/2>).6p (9/2,3/2)* | 測定値 | NIST | |
| 439.0196 nm | 4 | Ir II | emission | 5d6.6s2 5D → 5d7.(4P<5/2>).6p (5/2,1/2)* | 測定値 | NIST | |
| 443.3888 nm | データなし | Ir II | emission | 5d7.(2F).6s 3F → 5d6.6s.(6D<7/2>).6p (7/2,1/2)* | 測定値 | NIST | |
| 454.5672 nm | データなし | Ir II | emission | 5d7.(2H).6s 3H → 5d7.(4F<9/2>).6p (9/2,1/2)* | 測定値 | NIST | |
| 461.1752 nm | データなし | Ir II | emission | 5d7.(2F).6s 3F → 5d7.(4P<5/2>).6p (5/2,1/2)* | 測定値 | NIST | |
| 467.5844 nm | 5 | Ir II | emission | 5d7.(2G).6s 3G → 5d7.(4F<9/2>).6p (9/2,1/2)* | 測定値 | NIST | |
| 479.5262 nm | データなし | Ir II | emission | 5d6.6s2 5D → 5d7.(4F<9/2>).6p (9/2,1/2)* | 測定値 | NIST |
詳細な性質
共有結合半径（詳細）
- 共有結合半径（Pyykkö）
- 122 pm
- 共有結合半径（Pyykkö、二重結合）
- 115 pm
- 共有結合半径（Pyykkö、三重結合）
- 107 pm
ファンデルワールス半径
- Batsanov
- 200 pm
- Alvarez
- 241 pm
- UFF
- 284 pm
- MM3
- 236 pm
原子半径と金属半径
- 原子半径（Rahm）
- 240 pm
- 金属半径（C12）
- 136 pm
番号付けの尺度
- Mendeleev
- 65
- Pettifor
- 65
- Glawe
- 62
電気陰性度の尺度
- Ghosh
- 0
- Miedema
- 6
- Gunnarsson–Lundqvist
- 6
- Robles–Bartolotti
- 6
分極率と分散
- 双極子分極率
- 54 a.u.
- 双極子分極率（不確かさ）
- 7 a.u.
- C₆ (Gould–Bučko)
- 522 Ha·Bohr6
ミーデマパラメータ
- ミーデマモル体積
- 8.52 cm3/mol
- ミーデマ電子密度
- 6
供給リスクと経済性
- 生産集中度
- 60
- 相対供給リスク
- 8
- 埋蔵量の分布
- 95
- 政治的安定性（最大生産国）
- 44
- 政治的安定性（最大埋蔵国）
- 44
相転移と同素体
| 融点 | 2719.15 K |
| 沸点 | 4701.15 K |
酸化数の分類
専門参考データ
遮蔽定数 (14)
| n | 軌道 | σ |
|---|---|---|
| 1 | s | 1.4881 |
| 2 | p | 4.4624 |
| 2 | s | 20.1102 |
| 3 | d | 13.514 |
| 3 | p | 21.9311 |
| 3 | s | 22.7942 |
| 4 | d | 37.2628 |
| 4 | f | 38.6552 |
| 4 | p | 35.086 |
| 4 | s | 34.152 |
結晶半径の詳細 (3)
| 電荷 | CN | スピン | rcrystal (pm) | 由来 |
|---|---|---|---|---|
| 3 | VI | 82 | estimated, | |
| 4 | VI | 76.5 | from r^3 vs V plots, | |
| 5 | VI | 71 | estimated, from metallic oxides, |
同位体の崩壊形式 (64)
| 同位体 | モード | 強度 |
|---|---|---|
| 163 | p | — |
| 164 | p | — |
| 164 | A | — |
| 164 | B+ | — |
| 165 | p | — |
| 165 | A | — |
| 166 | A | 93% |
| 166 | p | 7% |
| 167 | A | 43.5% |
| 167 | p | 38.6% |
X線散乱因子 (515)
| エネルギー (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 2.22753 |
| 10.1617 | — | 2.30683 |
| 10.3261 | — | 2.38895 |
| 10.4931 | — | 2.474 |
| 10.6628 | — | 2.56207 |
| 10.8353 | — | 2.65417 |
| 11.0106 | — | 2.75003 |
| 11.1886 | — | 2.84935 |
| 11.3696 | — | 2.94781 |
| 11.5535 | — | 3.0118 |
追加データ
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
1×10-3 milligrams per kilogram
参考文献 (1)
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
Not Applicable
参考文献 (1)
Sources
Sources of this element.
Iridium occurs uncombined in nature with platinum and other metals of this family in alluvial deposits. It is recovered as a by-product from the nickel mining industry.
参考文献 (1)
- [6] Iridium https://periodic.lanl.gov/77.shtml
参考文献
(9)
Data deposited in or computed by PubChem
The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.
Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.
The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.
Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/
The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.
The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database
This section provides all form of data related to element Iridium.
The element property data was retrieved from publications.