Cerium (Ce)
lanthanideSolid
標準原子量
140.116 u電子配置
[Xe] 6s2 4f1 5d1融点
797.85 °C沸点
3423.85 °C密度
6770 kg/m³酸化数
+1, +2, +3, +4電気陰性度（Pauling）
1.12第1イオン化エネルギー
5.5386 eV発見年
1801原子半径
185 pm詳細
Cerium is the first lanthanide by atomic number and one of the most abundant rare-earth elements in the crust. It is a reactive, electropositive metal whose chemistry is unusual among lanthanides because both Ce³⁺ and Ce⁴⁺ are accessible in ordinary compounds. This Ce³⁺/Ce⁴⁺ redox pair, especially in oxides, makes cerium important in catalysts, polishing materials, glass treatment, and oxygen-storage applications.
Cerium is especially interesting because of its variable electronic structure. The energy of the inner 4f level is nearly the same as that of the outer (valence) electrons, and only small amounts of energy are required to change the relative occupancy of these electronic levels. This gives rise to dual valency states.
For example, a volume change of about 10 percent occurs when cerium is subjected to high pressures or low temperatures. Cesium's valence appears to change from about 3 to 4 when it is cooled or compressed. The low temperature behavior of cerium is complex.
Cerium is an iron-gray lustrous metal. It is malleable, and oxidizes very readily at room temperature, especially in moist air. Except for europium, cerium is the most reactive of the rare-earth metals. It decomposes slowly in cold water and rapidly in hot water.
Alkali solutions and dilute and concentrated acids attack the metal rapidly. The pure metal is likely to ignite if scratched with a knife.
Ceric slats are orange red or yellowish; cerous salts are usually white.
The name derives from the planetoid Ceres, which was discovered by the Italian astronomer Giuseppe Piazzi in 1801 and named for Ceres, the Roman goddess of agriculture and harvest. Two years later, the element cerium was discovered by the German chemist Martin-Heinrich Klaproth, who called it ochroeite earth because of its yellow colour.
Cerium was independently discovered at the same time by the Swedish chemist Jöns Jacob Berzelius and the Swedish mineralogist Wilhelm von Hisinger, who called it ceria. It was first isolated in 1875 by the American mineralogist and chemist William Frances Hillebrand and the American chemist Thomas H. Norton.
Cerium was discovered by Jöns Jacob Berzelius and Wilhelm von Hisinger, Swedish chemists, and independently by Martin Heinrich Klaproth, a German chemist, in 1803. Cerium is the most abundant of the rare earth elements and makes up about 0.0046% of the earth's crust. Today, cerium is primarily obtained through an ion exchange process from monazite sand ((Ce, La, Th, Nd, Y)PO4), a material rich in rare earth elements.
Cerium was named for the asteroid Ceres, which was discovered in 1801. The element was discovered two years later in 1803 by Klaproth and by Berzelius and Hisinger. In 1875 Hillebrand and Norton prepared the metal.
Pure cerium is a soft, silvery-gray metal that tarnishes readily in air. Fresh surfaces are metallic and bright, but oxidation quickly dulls them. The metal is ductile at room temperature, relatively low-melting for a lanthanide, and reactive enough that small particles can ignite when heated or abraded.
Cerium is widely used as cerium dioxide, CeO₂, in glass polishing powders and as an oxygen-storage component in automotive catalytic converters. Cerium compounds decolorize glass by oxidizing iron impurities and can also impart ultraviolet absorption. Mischmetal, a rare-earth alloy rich in cerium, is used in lighter flints and spark-producing alloys. Cerium is also used in some aluminum, magnesium, and iron alloys, where small additions can modify microstructure and oxidation behavior.
Pure cerium will ignite if it is scratched with a sharp object, but can be safely used if combined with other materials. Cerium is one of the rare earth elements used to make carbon arc lights which are used in the motion picture industry for studio lighting and projector lights. Cerium is also a component of Misch metal, a material that is used to make flints for lighters. Cerium is also used as a catalyst to refine petroleum and as an alloying agent to make special metals.
Cerium oxide (Ce2O3 and CeO2) is a component of the walls of self cleaning ovens and of incandescent lantern mantles. Cerium oxide is also used to polish glass surfaces. Ceric sulfate (Ce(So4)2) is used in some chemical analysis processes. Other cerium compounds are used to make some types of glass as well as to remove color from glass.
Cerium is a component of misch metal, which is extensively used in the manufacture of pyrophoric alloys for cigarette lighters. While cerium is not radioactive, the impure commercial grade may contain traces of thorium, which is radioactive. The oxide is an important constituent of incandescent gas mantles and is emerging as a hydrocarbon catalyst in self cleaning ovens where it can be incorporated into oven walls to prevent the collection of cooking residues.
As ceric sulfate is used extensively as a volumetric oxidizing agent in quantitative analysis. Cerium compounds are used in the manufacture of glass, both as a component and as a decolorizer.
The oxide is finding increased use as a glass polishing agent instead of rouge, for it polishes much faster than rouge. Cerium, with other rare earths, is used in carbon-arc lighting, especially in the motion picture industry. It is also useful as a catalyst in petroleum refining and in metallurgical and nuclear applications.
Isotopes in Earth/Planetary Science
When combined, 138La– 138Ce and 147Sm– 143Nd are two decay systems that are useful for studying processes affecting the light-rare-earth elements (lanthanum, cerium, praseodymium, neodymium, and samarium) and the igneous evolution of the Moon and Earth because different igneous materials have different cerium isotopic compositions (Fig. IUPAC.58.1) and can be used in mass balance investigations [419] H. Tazoe, H. Obata, T. Gamo. J. Anal. At. Spectrom.22, 616 (2007)., [420] M. Tanimizu, T. Tanaka. Geochim. Cosmochim. Acta66, 4007 (2002)..
Isotopes in Geochronology
138Ce is a radiogenic isotope produced by decay of 138La, with a half-life of 1.06×1011 years, one of the longest clocks in geochronology. Thus, the isotope-amount ratio n(138Ce)/n(142Ce) can be used for dating rocks on long time scales (billions of years) and can also be used as a chemical tracer in geochemical studies.
Isotopes in Medicine
144Ce (with a half-life of 0.78 year) has been used for brachytherapy applications in cells and vessels of the body. The half-life and specific activity of 144Ce give it a potential advantage over the commonly used isotope 192Ir of higher dose rate at shorter distances and lower irradiation of organs outside the tumor [424] V. O. Zilio, O. P. Joneja, Y. Popowski, F. O. Bochud, R. Chawla. Int. J. Radiat. Oncol. Biol. Phys.62, 585 (2005).. 144Ce enables the treatment of larger arteries as compared with 32P, another isotope commonly used for this style of radiotherapy.
Cerium commonly forms trivalent salts containing Ce³⁺ and tetravalent compounds containing Ce⁴⁺. Cerium dioxide, CeO₂, is the most important oxide and can reversibly lose small amounts of oxygen to form nonstoichiometric oxides, a property central to catalysis. Cerium(III) oxide, Ce₂O₃, is stable under reducing conditions. Cerium(III) chloride, CeCl₃, and cerium(III) nitrate, Ce(NO₃)₃, are common starting materials, while ceric ammonium nitrate, (NH₄)₂Ce(NO₃)₆, is a strong one-electron oxidant in laboratory chemistry.
See more information at the Cerium compound page.
Bulk cerium metal has low acute toxicity but is a fire risk as powder, turnings, or dust. It reacts with acids to release H₂ and should be kept from strong oxidizers and moisture when finely divided. Soluble cerium salts can irritate skin, eyes, and the respiratory tract, and inhalation of rare-earth dusts is an occupational concern. Natural cerium is not significantly radioactive for normal handling purposes.
Cerium occurs mainly in rare-earth minerals such as monazite, bastnäsite, and allanite, usually with other lanthanides. In surface environments it is commonly trivalent, but oxidation to Ce⁴⁺ can immobilize it as sparingly soluble oxides and hydroxides. This redox behavior produces cerium anomalies in marine sediments and some rocks, which are used as geochemical indicators of oxidation conditions.
Cerium is obtained as a by-product of rare-earth mining and separation, especially from bastnäsite and monazite concentrates. Because it is relatively abundant compared with many rare earths, supply is often tied more to separation capacity and demand for the whole rare-earth suite than to geological scarcity. Major demand comes from polishing powders, catalysts, glass additives, and pyrophoric alloys. Recycling is limited but possible from spent catalysts and industrial polishing slurries when collection and contamination levels make recovery practical.
Cerium is the most abundant so-called rare-earth metals. It is found in a number of minerals including allanite (also known as orthite), monazite, bastnasite, cerite, and samarskite. Monazite and bastnasite are presently the more important sources of cerium.
Large deposits of monazite (found on the beaches of Travancore, India and in river sands in Brazil), allanite (in the western United States), and bastnasite (in Southern California) will supply cerium, thorium, and the other rare-earth metals for many years to come.
Metallic cerium is prepared by metallothermic reduction techniques, such as reducing cerous fluoride with calcium, or using electrolysis of molten cerous chloride or others processes. The metallothermic technique produces high-purity cerium.
Cerium is made chiefly by neutron-capture processes in evolved stars, including the slow s-process and rapid r-process contributions. It is far less abundant cosmically than iron or oxygen but is one of the more abundant lanthanides. Cerium has been detected spectroscopically in some chemically peculiar stars, where rare-earth lines can be unusually strong.
- Cerium was named after the dwarf planet Ceres, discovered shortly before the element.
- CeO₂ can store and release oxygen without fully changing its crystal framework.
- Cerium is the only lanthanide with a common, stable tetravalent aqueous and solid-state chemistry.
- Finely divided cerium-rich alloys are the sparking material in many lighter flints.
- Cerium can show geochemical anomalies because Ce³⁺ is oxidized more readily than neighboring lanthanides.
画像
性質
物理的性質
- 原子半径（経験値）
- 185 pm 全元素の原子半径（経験値）を比較 →
- 共有結合半径
- 204 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
- 235 pm 全元素のファンデルワールス半径を比較 →
- 密度
- 6770 kg/m³ 全元素の密度を比較 →
- モル体積
- 0.021 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
- 797.85 °C 全元素の融点を比較 →
- 沸点
- 3423.85 °C 全元素の沸点を比較 →
- 熱伝導率
- 11.3 W/(m·K) 全元素の熱伝導率を比較 →
- 比熱容量
- 0.192 J/(g·K) 全元素の比熱容量を比較 →
- モル熱容量
- 26.94 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）
- 1.12 全元素の電気陰性度（Pauling）を比較 →
- 電子親和力
- 0.955 eV
- 第1イオン化エネルギー
- 5.5386 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
- 10.956038 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
- 20.19747 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
- 36.906127 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
- 65.550226 eV 全元素の第5イオン化エネルギーを比較 →
- 酸化数
- +1, +2, +3, +4 全元素の酸化数を比較 →
- 価電子
- 3 全元素の価電子を比較 →
- 電子配置
- [Xe] 6s2 4f1 5d1
熱力学的性質
- 融解熱
- 0.05658911 eV 全元素の融解熱を比較 →
- 蒸発熱
- 3.254392 eV 全元素の蒸発熱を比較 →
- 昇華熱
- 4.124994 eV
- 原子化熱
- 4.124994 eV
- 原子化エンタルピー
- 4.354045 eV
原子核
- 陽子数
- 58 全元素の陽子数を比較 →
- 中性子数
- 82 全元素の中性子数を比較 →
- 既知の同位体
- 41 全元素の既知の同位体を比較 →
- 安定同位体
- 1 全元素の安定同位体を比較 →
- 最も安定な同位体
- Ce-140
- 発見年
- 1801
存在度
- 存在度（地殻）
- 66.5 mg/kg 全元素の存在度（地殻）を比較 →
- 存在度（海洋）
- 1.2 × 10−6 mg/L 全元素の存在度（海洋）を比較 →
結晶構造
- 格子定数a
- 516 pm
電子構造
- 各電子殻の電子数
- 2, 8, 18, 19, 9, 2 全元素の各電子殻の電子数を比較 →
識別子
- CAS登録番号
- 7440-45-1 全元素のCAS登録番号を比較 →
- 項記号
- 1G°4
- InChI
- InChI=1S/Ce
- InChI Key
- GWXLDORMOJMVQZ-UHFFFAOYSA-N
電子配置 測定値
Ce: 4f¹ 5d¹ 6s²[Xe] 4f¹ 5d¹ 6s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹ 5d¹ 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 |
|---|---|---|---|
| 140 安定 | 139.9054431 ± 0.0000023 | 88.4500% | 安定 |
相／状態
理由: 融点（797.85 °C）より772.9 °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58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 |
|---|---|---|---|---|
| Ce I | 0 | 209 | 67 | 209 |
| Ce II | +1 | 560 | 283 | 560 |
| Ce III | +2 | 262 | 0 | 0 |
| Ce IV | +3 | 27 | 0 | 0 |
| Ce V | +4 | 5 | 0 | 0 |
準位データの収録状況 ?
| イオン | 電荷 | 準位 |
|---|---|---|
| Ce I | 0 | 953 |
| Ce II | +1 | 491 |
| Ce III | +2 | 227 |
| Ce IV | +3 | 17 |
| Ce V | +4 | 12 |
| Ce VI | +5 | 4 |
| Ce VII | +6 | 2 |
| Ce VIII | +7 | 2 |
| Ce IX | +8 | 2 |
| Ce X | +9 | 2 |
イオン半径
| 電荷 | 配位 | スピン | 半径 |
|---|---|---|---|
| +3 | 6 | データなし | 101 pm |
| +3 | 7 | データなし | 107 pm |
| +3 | 8 | データなし | 114.3 pm |
| +3 | 9 | データなし | 119.6 pm |
| +3 | 10 | データなし | 125 pm |
| +3 | 12 | データなし | 134 pm |
| +4 | 6 | データなし | 87 pm |
| +4 | 8 | データなし | 97 pm |
| +4 | 10 | データなし | 97 pm |
| +4 | 12 | データなし | 113.99999999999999 pm |
化合物
同位体 (1)
| 質量数 | 原子質量（u） | 天然存在比 | 半減期 | 崩壊形式 | |
|---|---|---|---|---|---|
| 140 安定 | 139.9054431 ± 0.0000023 | 88.4500% ± 0.0510% | 安定 | stable |
詳細な性質
共有結合半径（詳細）
- 共有結合半径（Pyykkö）
- 163 pm
- 共有結合半径（Pyykkö、二重結合）
- 137 pm
- 共有結合半径（Pyykkö、三重結合）
- 131 pm
ファンデルワールス半径
- Alvarez
- 288 pm
- UFF
- 355.6 pm
- MM3
- 274 pm
原子半径と金属半径
- 原子半径（Rahm）
- 282 pm
番号付けの尺度
- Mendeleev
- 15
- Pettifor
- 32
- Glawe
- 31
電気陰性度の尺度
- Ghosh
- 0
- Miedema
- 3
- Gunnarsson–Lundqvist
- 4
- Robles–Bartolotti
- 3
分極率と分散
- 双極子分極率
- 205 a.u.
- 双極子分極率（不確かさ）
- 20 a.u.
- C₆ (Gould–Bučko)
- 3480 Ha·Bohr6
ミーデマパラメータ
- ミーデマモル体積
- 21.62 cm3/mol
- ミーデマ電子密度
- 2
供給リスクと経済性
- 生産集中度
- 97
- 相対供給リスク
- 10
- 埋蔵量の分布
- 50
- 政治的安定性（最大生産国）
- 24
- 政治的安定性（最大埋蔵国）
- 24
相転移と同素体
| 融点 | 1072.15 K |
| 沸点 | 3716.15 K |
酸化数の分類
専門参考データ
遮蔽定数 (13)
| n | 軌道 | σ |
|---|---|---|
| 1 | s | 1.1519 |
| 2 | p | 4.2176 |
| 2 | s | 15.26 |
| 3 | d | 13.9147 |
| 3 | p | 19.0405 |
| 3 | s | 19.3408 |
| 4 | d | 32.3392 |
| 4 | f | 56.324 |
| 4 | p | 29.3936 |
| 4 | s | 28.32 |
結晶半径の詳細 (10)
| 電荷 | CN | スピン | rcrystal (pm) | 由来 |
|---|---|---|---|---|
| 3 | VI | 115 | from r^3 vs V plots, | |
| 3 | VII | 121 | estimated, | |
| 3 | VIII | 128.3 | from r^3 vs V plots, | |
| 3 | IX | 133.6 | from r^3 vs V plots, | |
| 3 | X | 139 | ||
| 3 | XII | 148 | calculated, | |
| 4 | VI | 101 | from r^3 vs V plots, | |
| 4 | VIII | 111 | from r^3 vs V plots, | |
| 4 | X | 121 | from r^3 vs V plots, | |
| 4 | XII | 128 |
同位体の崩壊形式 (54)
| 同位体 | モード | 強度 |
|---|---|---|
| 119 | B+ | — |
| 119 | B+p | — |
| 120 | B+ | — |
| 120 | B+p | — |
| 121 | B+ | 100% |
| 121 | B+p | 1% |
| 122 | B+ | — |
| 122 | B+p | — |
| 123 | B+ | 100% |
| 123 | B+p | — |
X線散乱因子 (508)
| エネルギー (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 1.28369 |
| 10.1617 | — | 1.26389 |
| 10.3261 | — | 1.24441 |
| 10.4931 | — | 1.22522 |
| 10.6628 | — | 1.20632 |
| 10.8353 | — | 1.18772 |
| 11.0106 | — | 1.16941 |
| 11.1886 | — | 1.15138 |
| 11.3696 | — | 1.13362 |
| 11.5535 | — | 1.11614 |
追加データ
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
6.65×101 milligrams per kilogram
参考文献 (1)
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
1.2×10-6 milligrams per liter
参考文献 (1)
Sources
Sources of this element.
Cerium is the most abundant so-called rare-earth metals. It is found in a number of minerals including allanite (also known as orthite), monazite, bastnasite, cerite, and samarskite. Monazite and bastnasite are presently the more important sources of cerium.
Large deposits of monazite (found on the beaches of Travancore, India and in river sands in Brazil), allanite (in the western United States), and bastnasite (in Southern California) will supply cerium, thorium, and the other rare-earth metals for many years to come.
Metallic cerium is prepared by metallothermic reduction techniques, such as reducing cerous fluoride with calcium, or using electrolysis of molten cerous chloride or others processes. The metallothermic technique produces high-purity cerium.
参考文献 (1)
- [6] Cerium https://periodic.lanl.gov/58.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 Cerium.
The element property data was retrieved from publications.