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58 lanthanum ← cerium → praseodymium
-
↑
Ce
↓
Th
General
Name, Symbol, Number cerium, Ce, 58
Chemical series lanthanides
Group, Period, Block n/a, 6, f
Appearance silvery white
Standard atomic weight 140. Lanthanum (ˈlænθənəm is a Chemical element with the symbol La and Atomic number 57 Praseodymium (ˌpreɪzioʊˈdɪmiəm or /ˌpreɪsioʊˈdɪmiəm/ is a Chemical element that has the symbol Pr and Atomic number 59 Thorium (ˈθɔːriəm is a Chemical element with the symbol Th and Atomic number 90 This is a typical display of the periodic table of the elements and contains the symbol and Atomic number of each element Wikipedia talkFeatured lists for an explanation of this and other inclusion tags below -->This is a list of Chemical elements, sorted by name Wikipedia talkFeatured lists for an explanation of this and other inclusion tags below -->This is a list of chemical elements by symbol, including the A table of Chemical elements ordered by Atomic number and color coded according to type of element In Chemistry a group, also known as a family, is a vertical column in the Periodic table of the Chemical elements There are 18 groups in Terminology The Trivial name " Rare earths " is sometimes used to describe all the lanthanoids together with Scandium and Yttrium In Chemistry a group, also known as a family, is a vertical column in the Periodic table of the Chemical elements There are 18 groups in In the Periodic table of the elements, a period is a horizontal row of the table A block of the Periodic table of elements is a set of adjacent groups The respective highest-energy electrons in each element in a block belong to the same Atomic Occurrence Scandium yttrium and the Lanthanides (except promethium tend to occur together in the Earth's crust and are relatively abundant compared with most D-block A period 6 element is one of the Chemical elements in the sixth row (or period) of the periodic table of the elements, including the Lanthanides The f-block of the Periodic table of the elements consists of those elements (sometimes referred to as the inner transition elements) for which in the The atomic mass (ma is the Mass of an atom most often expressed in unified atomic mass units The atomic mass may be considered to be the total mass 116(1)  g·mol−1
Electron configuration [Xe] 4f15d16s2
Electrons per shell 2, 8, 18, 19, 9, 2
Physical properties
Phase solid
Density (near r.t.) 6. In Atomic physics and Quantum chemistry, electron configuration is the arrangement of Electrons in an Atom, Molecule, or other Xenon (ˈzɛnɒn or) is a Chemical element represented by the symbol Xe. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J An electron shell may be crudely thought of as an Orbit followed by Electrons around an Atom nucleus. In the Physical sciences a phase is a Set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties A solid' object is in the States of matter characterized by resistance to Deformation and changes of Volume. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different Room temperature (also referred to as ambient temperature) is a common term to denote a certain Temperature within enclosed space at which humans are accustomed 770  g·cm−3
Liquid density at m.p. 6. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different The melting point of a solid is the temperature range at which it changes state from solid to Liquid. 55  g·cm−3
Melting point 1068 K
(795 °C, 1463 °F)
Boiling point 3716 K
(3443 °C, 6229 °F)
Heat of fusion 5. The melting point of a solid is the temperature range at which it changes state from solid to Liquid. The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic The Celsius Temperature scale was previously known as the centigrade scale. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 The boiling point of a liquid is the temperature at which the Vapor pressure of the liquid equals the environmental pressure surrounding the liquid The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic The Celsius Temperature scale was previously known as the centigrade scale. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 The standard Enthalpy of fusion (symbol \Delta{}H_{fus} also known as the heat of fusion or specific melting heat, is the amount of 46  kJ·mol−1
Heat of vaporization 398  kJ·mol−1
Specific heat capacity (25 °C) 26. The joule per mole (symbol J·mol-1 is an SI derived unit of energy per amount of material The enthalpy of vaporization, (symbol \Delta{}_{v}H also known as the heat of vaporization or heat of evaporation, is the Energy required The joule per mole (symbol J·mol-1 is an SI derived unit of energy per amount of material Specific heat capacity, also known simply as specific heat, is the measure of the heat energy required to increase the Temperature of a unit quantity 94  J·mol−1·K−1
Vapor pressure
P(Pa) 1 10 100 1 k 10 k 100 k
at T(K) 1992 2194 2442 2754 3159 3705
Atomic properties
Crystal structure cubic face centered
Oxidation states 3, 4
(mildly basic oxide)
Electronegativity 1. Vapor pressure (also known as equilibrium vapor pressure or saturation vapor pressure) is the Pressure of a Vapor in equilibrium In Mineralogy and Crystallography, a crystal structure is a unique arrangement of Atoms in a Crystal. In Chemistry, the oxidation state is an indicator of the degree of Oxidation of an Atom in a Chemical compound. In Chemistry, a base is most commonly thought of as an aqueous substance that can accept Protons This refers to the Brønsted-Lowry theory of acids and " Electronegativity " is the opposite of " Electropositivity," which describes an element's ability to donate electrons 12 (Pauling scale)
Ionization energies
(more)		 1st:  534. The ionization potential, ionization energy or EI of an Atom or Molecule is the Energy required to remove an Electron These tables list the Ionization energy in kJ/mol necessary to remove one mole of Electrons from one mole of neutral gaseous Atoms (first energy respectively 4  kJ·mol−1
2nd:  1050  kJ·mol−1
3rd:  1949  kJ·mol−1
Atomic radius 185  pm
Miscellaneous
Magnetic ordering no data
Electrical resistivity (r.t.) (β, poly) 828 nΩ·m
Thermal conductivity (300 K) 11. The joule per mole (symbol J·mol-1 is an SI derived unit of energy per amount of material Atomic radius, and more generally the size of an atom, is not a precisely defined Physical quantity, nor is it constant in all circumstances A picometre ( American spelling: picometer, symbol pm) is a unit of Length in the Metric system, equal to one trillionth In Physics, magnetism is one of the Phenomena by which Materials exert attractive or repulsive Forces on other Materials. Electrical resistivity (also known as specific electrical resistance) is a measure of how strongly a material opposes the flow of Electric current. Room temperature (also referred to as ambient temperature) is a common term to denote a certain Temperature within enclosed space at which humans are accustomed In Physics, thermal conductivity, k is the property of a material that indicates its ability to conduct Heat. 3  W·m−1·K−1
Thermal expansion (r.t.) (γ, poly)
6. When the Temperature of a substance changes the energy that is stored in the Intermolecular bonds between atoms changes Room temperature (also referred to as ambient temperature) is a common term to denote a certain Temperature within enclosed space at which humans are accustomed 3 µm/(m·K)
Speed of sound (thin rod) (20 °C) 2100 m/s
Young's modulus (γ form) 33. Sound is a vibration that travels through an elastic medium as a Wave. In Solid mechanics, Young's modulus (E is a measure of the Stiffness of an isotropic elastic material 6  GPa
Shear modulus (γ form) 13. In Materials science, shear modulus or modulus of rigidity, denoted by G, or sometimes S or μ, is defined as the ratio of Shear 5  GPa
Bulk modulus (γ form) 21. 5  GPa
Poisson ratio (γ form) 0. Poisson's ratio ( ν) named after Simeon Poisson, is the ratio of the relative contraction strain, or transverse strain (normal to 24
Mohs hardness 2. The Mohs scale of mineral hardness characterizes the scratch resistance of various Minerals through the ability of a harder material to scratch a softer material 5
Vickers hardness 270  MPa
Brinell hardness 412  MPa
CAS registry number 7440-45-1
Selected isotopes
Main article: Isotopes of cerium
iso NA half-life DM DE (MeV) DP
134Ce syn 3.16 days ε 0. The Vickers hardness test was developed in 1924 by Smith and Sandland as an alternative method to measure the Hardness of materials The Brinell scale characterizes the indentation Hardness of materials through the scale of penetration of an indenter loaded on a material test-piece CAS registry numbers are unique numerical identifiers for Chemical compounds Polymers biological sequences mixtures and Alloys They are also referred to Naturally occurring Cerium ( Ce) is composed of 3 stable Isotopes and 1 radioactive isotope 136Ce 138Ce 140Ce and 142Ce Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides In Chemistry, natural abundance (NA refers to the abundance Isotopes of a Chemical element as naturally found on a planet Half-Life (computer-game page here It's already listed in the disambiguation page Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. The decay energy is the Energy released by a Nuclear decay. The energy difference of the Reactants is often written as Q: where Q In Nuclear physics, a decay product, also known as a daughter product, daughter isotope or daughter nuclide, is a Nuclide A synthetic radioisotope is a Radionuclide that is not found in nature no natural process or mechanism exists which produces it or it is so unstable that it decays away in Seconds Years See also Natural history Geologic Electron capture (sometimes called inverse beta decay) is a Decay mode for Isotopes that will occur when there are too many Protons in the 500 134La
136Ce 0. Lanthanum (ˈlænθənəm is a Chemical element with the symbol La and Atomic number 57 185% 136Ce is stable with 78 neutrons
138Ce 0. Stable isotopes are chemical isotopes that are not Radioactive (to current knowledge This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. 251% 138Ce is stable with 80 neutrons
139Ce syn 137.640 days ε 0. Stable isotopes are chemical isotopes that are not Radioactive (to current knowledge This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. A synthetic radioisotope is a Radionuclide that is not found in nature no natural process or mechanism exists which produces it or it is so unstable that it decays away in Seconds Years See also Natural history Geologic Electron capture (sometimes called inverse beta decay) is a Decay mode for Isotopes that will occur when there are too many Protons in the 278 139La
140Ce 88. Lanthanum (ˈlænθənəm is a Chemical element with the symbol La and Atomic number 57 450% 140Ce is stable with 82 neutrons
141Ce syn 32.501 days β- 0. Stable isotopes are chemical isotopes that are not Radioactive (to current knowledge This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. A synthetic radioisotope is a Radionuclide that is not found in nature no natural process or mechanism exists which produces it or it is so unstable that it decays away in Seconds Years See also Natural history Geologic In Nuclear physics, beta decay is a type of Radioactive decay in which a Beta particle (an Electron or a Positron) is emitted 581 141Pr
142Ce 11. Praseodymium (ˌpreɪzioʊˈdɪmiəm or /ˌpreɪsioʊˈdɪmiəm/ is a Chemical element that has the symbol Pr and Atomic number 59 114% > 5×1016 years β-β- unknown 142Nd
144Ce syn 284.893 days β- 0. Seconds Years See also Natural history Geologic In the process of Beta decay, unstable nuclei decay by converting a Neutron in the nucleus to a Proton and emitting an Electron and an electron Neodymium (ˌniːoʊˈdɪmiəm is a Chemical element with the symbol Nd and Atomic number 60 A synthetic radioisotope is a Radionuclide that is not found in nature no natural process or mechanism exists which produces it or it is so unstable that it decays away in Seconds Years See also Natural history Geologic In Nuclear physics, beta decay is a type of Radioactive decay in which a Beta particle (an Electron or a Positron) is emitted 319 144Pr
References

Cerium (pronounced /ˈsɪəriəm/) is a chemical element with the symbol Ce and atomic number 58. Praseodymium (ˌpreɪzioʊˈdɪmiəm or /ˌpreɪsioʊˈdɪmiəm/ is a Chemical element that has the symbol Pr and Atomic number 59 Recommended values for many properties of the elements together with various references are collected on these data pages A chemical element is a type of Atom that is distinguished by its Atomic number; that is by the number of Protons in its nucleus. See also List of elements by atomic number In Chemistry and Physics, the atomic number (also known as the proton

Contents

Notable characteristics

Cerium is a silvery metal, belonging to the lanthanide group. Terminology The Trivial name " Rare earths " is sometimes used to describe all the lanthanoids together with Scandium and Yttrium It resembles iron in color and luster, but is soft, and both malleable and ductile. Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Cerium has the longest liquid range of any non-radioactive element: 2648 °C (795 °C to 3443 °C) or 4766 °F (1463 °F to 6229 °F). (Thorium has a longer liquid range. Thorium (ˈθɔːriəm is a Chemical element with the symbol Th and Atomic number 90 )

Although cerium belongs to chemical elements group called rare earth metals, it is in fact more common than lead. Rare earth elements and rare earth metals are according to IUPAC, the collection of seventeen Chemical elements in the Periodic table, namely Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly Cerium is available in relatively large quantities (68 ppm in Earth’s crust). It is used in some rare-earth alloys.

Among rare earth elements only europium is more reactive. Europium (jʊˈroʊpiəm is a Chemical element with the symbol Eu and Atomic number 63 It tarnishes readily in the air. Alkali solutions and dilute and concentrated acids attack the metal rapidly. Cerium oxidizes slowly in cold water and rapidly in hot water. The pure metal can ignite if scratched.

Cerium(IV) (ceric) salts are orange red or yellowish, whereas cerium(III) (cerous) salts are usually white or colorless. Both oxidation states absorb ultraviolet light strongly. Cerium(III) can be used to make glasses that are colorless, yet absorb ultraviolet light almost completely. Cerium can be readily detected in rare earth mixtures by a very sensitive qualitative test: addition of ammonia and hydrogen peroxide to an aqueous solution of lanthanides produces a characteristic dark brown color if cerium is present. Ammonia is a compound with the formula N[[hydrogen H3]] It is normally encountered as a Gas with a characteristic pungent Odor Hydrogen peroxide (H2O2 is a very pale blue liquid which appears colorless in a dilute solution slightly more Viscous than water


Phase diagram of cerium
Phase diagram of cerium


Applications

Uses of cerium:

History

Cerium was discovered in Bastnäs in Sweden by Jöns Jakob Berzelius and Wilhelm Hisinger, and independently in Germany by Martin Heinrich Klaproth, both in 1803. Bastnäs ( Swedish: Bastnäs or Bastnäsfältet) is an ore-field in Riddarhyttan, Västmanland, Sweden. "Sverige" redirects here For other uses see Sweden (disambiguation and Sverige (disambiguation. Friherre Jöns Jacob Berzelius (20 August 1779 &ndash 7 August 1848 was a Swedish chemist Wilhelm Hisinger (1766-1852 was a Swedish Chemist who in 1807 working in coordination with Jöns Jakob Berzelius, noted that in Electrolysis Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. Martin Heinrich Klaproth ( 1 December 1743 – 1 January 1817) was a German Chemist. Cerium was so named by Berzelius after the dwarf planet Ceres, discovered two years earlier (1801). Ceres (ˈsɪəriːz As originally isolated, cerium was in the form of its oxide, and was named ceria, a term that is still used. The metal itself was too electropositive to be isolated by then-current smelting technology, a characteristic of earth metals in general. However, the development of electrochemistry by Humphry Davy was only five years into the future, and then the earths were well on their way to yielding up the metals they contained. Electrochemistry is a branch of Chemistry that studies Chemical reactions which take place in a Solution at the interface of an electron conductor Sir Humphry Davy 1st Baronet FRS MRIA (17 December 1778 &ndash 29 May 1829 was a British Chemist and inventor Ceria, as isolated in 1803, contained all of the lanthanides present in the cerite ore from Bastnaes, Sweden, and thus only contained about 45% of what is now known to be pure ceria. It was not until Mosander succeeded in removing lanthana and "didymia" in the late 1830s, that ceria was obtained pure. As an historical aside: Wilhelm Hisinger was a wealthy mine owner and amateur scientist, and sponsor of Berzelius. He owned or controlled the mine at Bastnaes, and had been trying for years to find out the composition of the abundant heavy gangue rock (the "Tungstein of Bastnaes"), now known as cerite, that he had in his mine. Mosander and his family lived for many years in the same house as Berzelius, and the former was undoubtedly persuaded by the latter to investigate ceria further. When the rare earths were first discovered, since they were strong bases like the oxides of calcium or magnesium, they were thought to be divalent. Thus, "ceric" cerium was thought to be trivalent, and the oxidation state ratio was therefore thought to be 1. 5. Berzelius was extremely annoyed to keep on getting the ratio 1. 33. He was after all one of the finest analytical chemists in Europe. But he was a better analyst than he thought, since 1. 33 was the correct answer!

Occurrence

Cerium is the most abundant of the rare earth elements, making up about 0. Rare earth elements and rare earth metals are according to IUPAC, the collection of seventeen Chemical elements in the Periodic table, namely 0046% of the Earth's crust by weight. In Geology, a crust is the outermost solid shell of a planet or moon It is found in a number of minerals including allanite (also known as orthite)—(Ca, Ce, La, Y)2(Al, Fe)3(SiO4)3(OH), monazite (Ce, La, Th, Nd, Y)PO4, bastnasite (Ce, La, Y)CO3F, hydroxylbastnasite (Ce, La, Nd)CO3(OH, F), rhabdophane (Ce, La, Nd)PO4-H2O, zircon (ZrSiO4), and synchysite Ca(Ce, La, Nd, Y)(CO3)2F. Allanite is a sorosilicate group of minerals within the broader Epidote group that contain a significant amount of Rare earth elements It has the general In Geology, the Mineral monazite is a reddish-brown Phosphate -containing rare earth metals and an important source of Thorium The mineral bastnäsite is one of a family of three Carbonate - Fluoride minerals Hydroxyl in Chemistry stands for a molecule consisting of an Oxygen atom and a Hydrogen atom connected by a Covalent bond. The mineral bastnäsite is one of a family of three Carbonate - Fluoride minerals Zircon is a Mineral belonging to the group of nesosilicates. Its chemical name is Zirconium silicate and its corresponding chemical formula is Monazite and bastnasite are presently the two most important sources of cerium.

Cerium is most often prepared via an ion exchange process that uses monazite sands as its cerium source. Ion exchange is an exchange of Ions between two Electrolytes or between an electrolyte Solution and a complex.

Large deposits of monazite, allanite, and bastnasite will supply cerium, thorium, and other rare-earth metals for many years to come. In Geology, the Mineral monazite is a reddish-brown Phosphate -containing rare earth metals and an important source of Thorium Allanite is a sorosilicate group of minerals within the broader Epidote group that contain a significant amount of Rare earth elements It has the general The mineral bastnäsite is one of a family of three Carbonate - Fluoride minerals

See also Category:Lanthanide minerals

Compounds

Cerium(IV)-sulfate
Cerium(IV)-sulfate

Cerium has two common oxidation states, +3 and +4. In Chemistry, the oxidation state is an indicator of the degree of Oxidation of an Atom in a Chemical compound. The most common compound of cerium is cerium(IV) oxide (CeO2), which is used as "jeweller's rouge" as well as in the walls of some self-cleaning ovens. Cerium(IV oxide, ceric oxide, ceria, or sometimes simply cerium oxide or cerium dioxide, is a pale yellow-white powder CeO2 A self-cleaning oven is an Oven which uses high temperature (approximately 900 degrees Fahrenheit or 500 degrees Celsius) to burn off leftovers from baking Two common oxidising agents used in titrations are ammonium cerium(IV) sulfate (ceric ammonium sulfate, (NH4)2Ce(SO4)3) and ammonium cerium(IV) nitrate (ceric ammonium nitrate or CAN, (NH4)2Ce(NO3)6). Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state Titration is a common laboratory method of Quantitative chemical analysis that is used to determine the unknown Concentration of a known Reactant Ammonium cerium(IV sulfate is a Chemical compound. Ceric ammonium nitrate, or in lab jargon "CAN" is the Chemical compound with the formula ( NH4)2Ce(NO36 Cerium also forms a chloride, CeCl3 or cerium(III) chloride, used to facilitate reactions at carbonyl groups in organic chemistry. The chloride Ion is formed when the element Chlorine picks up one Electron to form an Anion (negatively-charged ion Cl&minus Cerium(III chloride (CeCl3 also known as cerous chloride or cerium trichloride is a compound of Cerium and Chlorine. In Organic chemistry, a carbonyl group is a Functional group composed of a Carbon Atom double-bonded to an Oxygen Organic chemistry is a discipline within Chemistry which involves the scientific study of the structure properties composition reactions, and preparation Other compounds include cerium(III) carbonate (Ce2(CO3)3), cerium(III) fluoride (CeF3), cerium(III) oxide (Ce2O3), as well as cerium(IV) sulfate (ceric sulfate, Ce(SO4)2) and cerium(III) triflate (Ce(OSO2CF3)3). Cerium(IV sulfate also called ceric sulfate is a yellow to yellow/orange Chemical compound.

The two oxidation states of cerium differ enormously in basicity: cerium(III) is a strong base, comparable to the other trivalent lanthanides, but cerium(IV) is weak. This difference has always allowed cerium to be by far the most readily isolated and purified of all the lanthanides, otherwise a notoriously difficult group of elements to separate. A wide range of procedures have been devised over the years to exploit the difference. Among the better ones:

  1. Leaching the mixed hydroxides with dilute nitric acid: the trivalent lanthanides dissolve in cerium-free condition, and tetravalent cerium remains in the insoluble residue as a concentrate to be further purified by other means. A variation on this uses hydrochloric acid and the calcined oxides from bastnaesite, but the separation is less sharp.
  2. Precipitating cerium from a nitrate or chloride solution using potassium permanganate and sodium carbonate in a 1:4 molar ratio.
  3. Boiling rare-earth nitrate solutions with potassium bromate and marble chips.

Using the classical methods of rare-earth separation, there was a considerable advantage to a strategy of removing cerium from the mixture at the beginning. Cerium typically comprised 45% of the cerite or monazite rare earths, and removing it early greatly reduced the bulk of what needed to be further processed (or the cost of reagents to be associated with such processing). However, not all cerium purification methods relied on basicity. Ceric ammonium nitrate [ammonium hexanitratocerate(IV)] crystallization from nitric acid was one purification method. Cerium(IV) nitrate (hexanitratoceric acid) was more readily extractable into certain solvents (e. g. tri-n-butyl phosphate) than the trivalent lanthanides. However, modern practice in China seems to be to do purification of cerium by counter-current solvent extraction, in its trivalent form, just like the other lanthanides.

Cerium(IV) is a strong oxidant under acidic conditions, but stable under alkaline conditions, when it is cerium(III) that becomes a strong reductant, easily oxidized by molecular dioxygen (or air). This ease of oxidation under alkaline conditions leads to the occasional geochemical parting of the ways between cerium and the trivalent light lanthanides under supergene weathering conditions, leading variously to the "negative cerium anomaly" or to the formation of the mineral cerianite. Air-oxidation of alkaline cerium(III) is the most economical way to get to cerium(IV), which can then be handled in acid solution.

See also Category:Cerium compounds

Isotopes

Main article: isotopes of cerium

Naturally-occurring cerium is composed of 4 stable isotopes; 136Ce, 138Ce, 140Ce, and 142Ce with 140Ce being the most abundant (88. Naturally occurring Cerium ( Ce) is composed of 3 stable Isotopes and 1 radioactive isotope 136Ce 138Ce 140Ce and 142Ce Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides 48% natural abundance). In Chemistry, natural abundance (NA refers to the abundance Isotopes of a Chemical element as naturally found on a planet 136Ce and 142Ce are predicted to be double beta active but no signs of activity were ever observed (for 142Ce, the lower limit on half-life is 5×1016 years). In the process of Beta decay, unstable nuclei decay by converting a Neutron in the nucleus to a Proton and emitting an Electron and an electron Half-Life (computer-game page here It's already listed in the disambiguation page 26 radioisotopes have been characterized with the most long-lived being 144Ce with a half-life of 284. A radionuclide is an Atom with an unstable nucleus, which is a nucleus characterized by excess energy which is available to be imparted either to a newly-created 893 days, 139Ce with a half-life of 137. 640 days, and 141Ce with a half-life of 32. 501 days. All of the remaining radioactive isotopes have half-lives that are less than 4 days and the majority of these have half-lives that are less than 10 minutes. Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. This element also has 2 meta states. A nuclear isomer is a Metastable state of an Atomic nucleus caused by the excitation of one or more of its Nucleons A nuclear isomer occupies

The known isotopes of cerium range in atomic weight from 123 u (123Ce) to 152 u (152Ce). The atomic mass (ma is the Mass of an atom most often expressed in unified atomic mass units The atomic mass may be considered to be the total mass The unified atomic mass unit ( u) or Dalton ( Da) or sometimes universal mass unit, is an unit of Mass used to express

Cerium 144 is a high-yield product of nuclear fission; the ORNL Fission Product Pilot Plant separated substantial quantities of cerium-144 from reactor waste, and it was used in the Aircraft Nuclear Propulsion and SNAP programs. Nuclear fission is the splitting of the nucleus of an atom into parts (lighter nuclei) often producing Free neutrons and other smaller nuclei which may Oak Ridge National Laboratory ( ORNL) is a multiprogram science and technology National laboratory managed for the United States Department of Energy by The Fission Product Pilot Plant, building 3515 at Oak Ridge National Laboratory, was built in 1948 to extract radioactive isotopes from liquid radioactive waste Aircraft Nuclear Propulsion (ANP was a United States Air Force program which worked to develop a nuclear propulsion system for aircraft The Systems Nuclear Auxiliary Power Program (SNAP was a program of experimental Radioisotope thermoelectric generators (RTGs and space Nuclear reactors flown during

Precautions

Cerium, like all rare-earth metals, is of low to moderate toxicity. Cerium is a strong reducing agent and ignites spontaneously in air at 65 to 80 °C (150 to 175 °F). Fumes from cerium fires are toxic. Water should not be used to stop cerium fires, as cerium reacts with water to produce hydrogen gas. Workers exposed to cerium have experienced itching, sensitivity to heat, and skin lesions. Animals injected with large doses of cerium have died due to cardiovascular collapse.

Cerium(IV) oxide is a powerful oxidizing agent at high temperatures and will react with combustible organic materials. While cerium is not radioactive, the impure commercial grade may contain traces of thorium, which is radioactive. Cerium serves no known biological function.

Popular culture references

One chapter in Primo Levi's book The Periodic Table called Cerium, the element saves the hero from starvation. Primo Michele Levi ( July 31, 1919 &ndash April 11, 1987) was a Jewish Italian Chemist, Holocaust survivor

References

External links

Dictionary

cerium

-noun

  1. A metallic chemical element (symbol Ce) with an atomic number of 58.
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