Cerium (Ce)
lanthanideSolid
Bobot Atom Standar
140,116 uKonfigurasi elektron
[Xe] 6s2 4f1 5d1Titik lebur
797,85 °CTitik didih
3423,85 °CMassa jenis
6770 kg/m³Bilangan oksidasi
+1, +2, +3, +4Keelektronegatifan (Pauling)
1,12Energi ionisasi (ke-1)
5,5386 eVTahun penemuan
1801Jari-jari atom
185 pmDetail
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.
Gambar
Sifat
Fisika
- Jari-jari atom (empiris)
- 185 pm Bandingkan Jari-jari atom (empiris) semua unsur →
- Jari-jari kovalen
- 204 pm Bandingkan Jari-jari kovalen semua unsur →
- Jari-jari van der Waals
- 235 pm Bandingkan Jari-jari van der Waals semua unsur →
- Massa jenis
- 6770 kg/m³ Bandingkan Massa jenis semua unsur →
- Volume molar
- 0,021 L/mol
- Fase pada STP
- Padat Bandingkan Fase pada STP semua unsur →
- Titik lebur
- 797,85 °C Bandingkan Titik lebur semua unsur →
- Titik didih
- 3423,85 °C Bandingkan Titik didih semua unsur →
- Konduktivitas termal
- 11,3 W/(m·K) Bandingkan Konduktivitas termal semua unsur →
- Kapasitas kalor spesifik
- 0,192 J/(g·K) Bandingkan Kapasitas kalor spesifik semua unsur →
- Kapasitas kalor molar
- 26,94 J/(mol·K) Bandingkan Kapasitas kalor molar semua unsur →
- Struktur kristal
- Kubik berpusat muka Bandingkan Struktur kristal semua unsur →
Kimia
- Keelektronegatifan (Pauling)
- 1,12 Bandingkan Keelektronegatifan (Pauling) semua unsur →
- Afinitas elektron
- 0,955 eV
- Energi ionisasi (ke-1)
- 5,5386 eV Bandingkan Energi ionisasi (ke-1) semua unsur →
- Energi ionisasi (ke-2)
- 10,956038 eV Bandingkan Energi ionisasi (ke-2) semua unsur →
- Energi ionisasi (ke-3)
- 20,19747 eV Bandingkan Energi ionisasi (ke-3) semua unsur →
- Energi ionisasi (ke-4)
- 36,906127 eV Bandingkan Energi ionisasi (ke-4) semua unsur →
- Energi ionisasi (ke-5)
- 65,550226 eV Bandingkan Energi ionisasi (ke-5) semua unsur →
- Bilangan oksidasi
- +1, +2, +3, +4 Bandingkan Bilangan oksidasi semua unsur →
- Elektron valensi
- 3 Bandingkan Elektron valensi semua unsur →
- Konfigurasi elektron
- [Xe] 6s2 4f1 5d1
Termodinamika
- Kalor peleburan
- 0,05658911 eV Bandingkan Kalor peleburan semua unsur →
- Kalor penguapan
- 3,254392 eV Bandingkan Kalor penguapan semua unsur →
- Kalor sublimasi
- 4,124994 eV
- Kalor atomisasi
- 4,124994 eV
- Entalpi atomisasi
- 4,354045 eV
Nuklir
- Proton
- 58 Bandingkan Proton semua unsur →
- Neutron
- 82 Bandingkan Neutron semua unsur →
- Isotop yang diketahui
- 41 Bandingkan Isotop yang diketahui semua unsur →
- Isotop stabil
- 1 Bandingkan Isotop stabil semua unsur →
- Isotop paling stabil
- Ce-140
- Tahun penemuan
- 1801
Kelimpahan
- Kelimpahan (kerak Bumi)
- 66,5 mg/kg Bandingkan Kelimpahan (kerak Bumi) semua unsur →
- Kelimpahan (samudra)
- 1,2 × 10−6 mg/L Bandingkan Kelimpahan (samudra) semua unsur →
Struktur Kristal
- Konstanta kisi a
- 516 pm
Struktur Elektronik
- Elektron per kulit
- 2, 8, 18, 19, 9, 2 Bandingkan Elektron per kulit semua unsur →
Pengenal
- Nomor CAS
- 7440-45-1 Bandingkan Nomor CAS semua unsur →
- Simbol term
- 1G°4
- InChI
- InChI=1S/Ce
- Kunci InChI
- GWXLDORMOJMVQZ-UHFFFAOYSA-N
Konfigurasi Elektron Diukur
Ce: 4f¹ 5d¹ 6s²[Xe] 4f¹ 5d¹ 6s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹ 5d¹ 6s²Model atom
Isotop mengubah jumlah neutron, massa, dan kestabilan — bukan konfigurasi elektron atom netral.
Model atom skematis, tidak sesuai skala.
Sidik Jari Atom
Spektrum Emisi / Absorpsi
Distribusi Isotop
| Nomor massa | Massa atom (u) | Kelimpahan alami | Waktu paruh |
|---|---|---|---|
| 140 Stabil | 139,9054431 ± 0,0000023 | 88,4500% | Stabil |
Fase / Wujud
Alasan: 772,9 °C di bawah titik lebur (797,85 °C)
Skematis, tidak sesuai skala
Titik transisi fase
Energi transisi
Energi yang diperlukan untuk meleburkan 1 mol pada titik lebur
Energi yang diperlukan untuk menguapkan 1 mol pada titik didih
Energi yang diperlukan untuk menyublimkan 1 mol pada titik sublimasi
Massa jenis
Pada kondisi standar
Pada kondisi standar
Spektrum Atom
Menampilkan 10 dari 58. Diurutkan berdasarkan muatan ion (menaik).
Data Garis Spektrum ?
| Ion | Muatan | Total garis | Probabilitas transisi | Penamaan tingkat energi |
|---|---|---|---|---|
| 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 |
Data Tingkat Energi ?
| Ion | Muatan | Tingkat energi |
|---|---|---|
| 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 |
Jari-jari Ion
| Muatan | Koordinasi | Spin | Jari-jari |
|---|---|---|---|
| +3 | 6 | Tidak tersedia | 101 pm |
| +3 | 7 | Tidak tersedia | 107 pm |
| +3 | 8 | Tidak tersedia | 114.3 pm |
| +3 | 9 | Tidak tersedia | 119.6 pm |
| +3 | 10 | Tidak tersedia | 125 pm |
| +3 | 12 | Tidak tersedia | 134 pm |
| +4 | 6 | Tidak tersedia | 87 pm |
| +4 | 8 | Tidak tersedia | 97 pm |
| +4 | 10 | Tidak tersedia | 97 pm |
| +4 | 12 | Tidak tersedia | 113.99999999999999 pm |
Senyawa
Isotop (1)
| Nomor massa | Massa atom (u) | Kelimpahan alami | Waktu paruh | Mode peluruhan | |
|---|---|---|---|---|---|
| 140 Stabil | 139,9054431 ± 0,0000023 | 88,4500% ± 0,0510% | Stabil | stable |
Sifat Lanjutan
Jari-jari Kovalen (Lanjutan)
- Jari-jari kovalen (Pyykkö)
- 163 pm
- Jari-jari kovalen (Pyykkö, ikatan rangkap dua)
- 137 pm
- Jari-jari kovalen (Pyykkö, ikatan rangkap tiga)
- 131 pm
Jari-jari van der Waals
- Alvarez
- 288 pm
- UFF
- 355,6 pm
- MM3
- 274 pm
Jari-jari Atom & Logam
- Jari-jari atom (Rahm)
- 282 pm
Skala Penomoran
- Mendeleev
- 15
- Pettifor
- 32
- Glawe
- 31
Skala Keelektronegatifan
- Ghosh
- 0
- Miedema
- 3
- Gunnarsson–Lundqvist
- 4
- Robles–Bartolotti
- 3
Polarizabilitas & Dispersi
- Polarizabilitas dipol
- 205 a.u.
- Polarizabilitas dipol (ketidakpastian)
- 20 a.u.
- C₆ (Gould–Bučko)
- 3480 Ha·Bohr6
Parameter Miedema
- Volume molar Miedema
- 21,62 cm3/mol
- Kerapatan elektron Miedema
- 2
Risiko Pasokan & Ekonomi
- Konsentrasi produksi
- 97
- Risiko pasokan relatif
- 10
- Distribusi cadangan
- 50
- Stabilitas politik (produsen terbesar)
- 24
- Stabilitas politik (pemilik cadangan terbesar)
- 24
Transisi Fase & Alotrop
| Titik lebur | 1072,15 K |
| Titik didih | 3716,15 K |
Kategori Bilangan Oksidasi
Data Referensi Lanjutan
Konstanta Pemerisaian (13)
| n | Orbital | 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 |
Detail Jari-jari Kristal (10)
| Muatan | CN | Spin | rcrystal (pm) | Asal |
|---|---|---|---|---|
| 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 |
Mode Peluruhan Isotop (54)
| Isotop | Mode | Intensitas |
|---|---|---|
| 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 | — |
Faktor Hamburan Sinar-X (508)
| Energi (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 |
Data Tambahan
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
6.65×101 milligrams per kilogram
Referensi (1)
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
1.2×10-6 milligrams per liter
Referensi (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.
Referensi (1)
- [6] Cerium https://periodic.lanl.gov/58.shtml
Referensi
(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.