Naturally occurring

cerium Cerium is a chemical element with the symbol Ce and atomic number 58. Cerium is a soft, ductile, and silvery-white metal that tarnishes when exposed to air. Cerium is the second element in the lanthanide series, and while it often shows the +3 ...

(₅₈Ce) is composed of 4 stable

isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numb ...

s: ¹³⁶Ce, ¹³⁸Ce, ¹⁴⁰Ce, and ¹⁴²Ce, with ¹⁴⁰Ce being the most abundant (88.48%

natural abundance In physics, natural abundance (NA) refers to the abundance of isotopes of a chemical element as naturally found on a planet. The relative atomic mass (a weighted average, weighted by mole-fraction abundance figures) of these isotopes is the atomi ...

) and the only one theoretically stable; ¹³⁶Ce, ¹³⁸Ce, and ¹⁴²Ce are predicted to undergo

double beta decay In nuclear physics, double beta decay is a type of radioactive decay in which two neutrons are simultaneously transformed into two protons, or vice versa, inside an atomic nucleus. As in single beta decay, this process allows the atom to move clos ...

but this process has never been observed. There are 35

radioisotope A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferr ...

s that have been characterized, with the most stable being ¹⁴⁴Ce, with a half-life of 284.893 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 Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consi ...

isotopes have half-lives that are less than 4 days and the majority of these have half-lives that are less than 10 minutes. This element also has 10

meta state A nuclear isomer is a metastable state of an atomic nucleus, in which one or more nucleons (protons or neutrons) occupy higher energy levels than in the ground state of the same nucleus. "Metastable" describes nuclei whose excited states have ...

s. The isotopes of cerium range in

atomic weight Relative atomic mass (symbol: ''A''; sometimes abbreviated RAM or r.a.m.), also known by the deprecated synonym atomic weight, is a dimensionless physical quantity defined as the ratio of the average mass of atoms of a chemical element in a giv ...

from 119 u (¹¹⁹Ce) to 157 u (¹⁵⁷Ce).

List of isotopes

, - , ¹¹⁹Ce , style="text-align:right" , 58 , style="text-align:right" , 61 , 118.95276(64)# , 200# ms , β⁺ , ¹¹⁹La , 5/2+# , , , - , ¹²⁰Ce , style="text-align:right" , 58 , style="text-align:right" , 62 , 119.94664(75)# , 250# ms , β⁺ , ¹²⁰La , 0+ , , , - , ¹²¹Ce , style="text-align:right" , 58 , style="text-align:right" , 63 , 120.94342(54)# , 1.1(1) s , β⁺ , ¹²¹La , (5/2)(+#) , , , - , rowspan=2, ¹²²Ce , rowspan=2 style="text-align:right" , 58 , rowspan=2 style="text-align:right" , 64 , rowspan=2, 121.93791(43)# , rowspan=2, 2# s , β⁺ , ¹²²La , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁺, p , ¹²¹Ba , - , rowspan=2, ¹²³Ce , rowspan=2 style="text-align:right" , 58 , rowspan=2 style="text-align:right" , 65 , rowspan=2, 122.93540(32)# , rowspan=2, 3.8(2) s , β⁺ , ¹²³La , rowspan=2, (5/2)(+#) , rowspan=2, , rowspan=2, , - , β⁺, p , ¹²²Ba , - , ¹²⁴Ce , style="text-align:right" , 58 , style="text-align:right" , 66 , 123.93041(32)# , 9.1(12) s , β⁺ , ¹²⁴La , 0+ , , , - , rowspan=2, ¹²⁵Ce , rowspan=2 style="text-align:right" , 58 , rowspan=2 style="text-align:right" , 67 , rowspan=2, 124.92844(21)# , rowspan=2, 9.3(3) s , β⁺ , ¹²⁵La , rowspan=2, (7/2−) , rowspan=2, , rowspan=2, , - , β⁺, p , ¹²⁴Ba , - , ¹²⁶Ce , style="text-align:right" , 58 , style="text-align:right" , 68 , 125.92397(3) , 51.0(3) s , β⁺ , ¹²⁶La , 0+ , , , - , ¹²⁷Ce , style="text-align:right" , 58 , style="text-align:right" , 69 , 126.92273(6) , 29(2) s , β⁺ , ¹²⁷La , 5/2+# , , , - , ¹²⁸Ce , style="text-align:right" , 58 , style="text-align:right" , 70 , 127.91891(3) , 3.93(2) min , β⁺ , ¹²⁸La , 0+ , , , - , ¹²⁹Ce , style="text-align:right" , 58 , style="text-align:right" , 71 , 128.91810(3) , 3.5(3) min , β⁺ , ¹²⁹La , (5/2+) , , , - , ¹³⁰Ce , style="text-align:right" , 58 , style="text-align:right" , 72 , 129.91474(3) , 22.9(5) min , β⁺ , ¹³⁰La , 0+ , , , - , style="text-indent:1em" , ^130mCe , colspan="3" style="text-indent:2em" , 2453.6(3) keV , 100(8) ns , , , (7−) , , , - , ¹³¹Ce , style="text-align:right" , 58 , style="text-align:right" , 73 , 130.91442(4) , 10.2(3) min , β⁺ , ¹³¹La , (7/2+) , , , - , style="text-indent:1em" , ^131mCe , colspan="3" style="text-indent:2em" , 61.8(1) keV , 5.0(10) min , β⁺ , ¹³¹La , (1/2+) , , , - , ¹³²Ce , style="text-align:right" , 58 , style="text-align:right" , 74 , 131.911460(22) , 3.51(11) h , β⁺ , ¹³²La , 0+ , , , - , style="text-indent:1em" , ^132mCe , colspan="3" style="text-indent:2em" , 2340.8(5) keV , 9.4(3) ms , IT , ¹³²Ce , (8−) , , , - , ¹³³Ce , style="text-align:right" , 58 , style="text-align:right" , 75 , 132.911515(18) , 97(4) min , β⁺ , ¹³³La , 1/2+ , , , - , style="text-indent:1em" , ^133mCe , colspan="3" style="text-indent:2em" , 37.1(8) keV , 4.9(4) d , β⁺ , ¹³³La , 9/2− , , , - , ¹³⁴Ce , style="text-align:right" , 58 , style="text-align:right" , 76 , 133.908925(22) , 3.16(4) d , EC , ¹³⁴La , 0+ , , , - , ¹³⁵Ce , style="text-align:right" , 58 , style="text-align:right" , 77 , 134.909151(12) , 17.7(3) h , β⁺ , ¹³⁵La , 1/2(+) , , , - , style="text-indent:1em" , ^135mCe , colspan="3" style="text-indent:2em" , 445.8(2) keV , 20(1) s , IT , ¹³⁵Ce , (11/2−) , , , - , ¹³⁶Ce , style="text-align:right" , 58 , style="text-align:right" , 78 , 135.907172(14) , colspan=3 align=center,

Observationally Stable Stable nuclides are nuclides that are not radioactive and so (unlike radionuclides) do not spontaneously undergo radioactive decay. When such nuclides are referred to in relation to specific elements, they are usually termed stable isotopes. Th ...

Theorized to undergo β⁺β⁺ decay to ¹³⁶Ba with a

half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable at ...

over 38×10¹⁵ years , 0+ , 0.00185(2) , 0.00185–0.00186 , - , style="text-indent:1em" , ^136mCe , colspan="3" style="text-indent:2em" , 3095.5(4) keV , 2.2(2) µs , , , 10+ , , , - , ¹³⁷Ce , style="text-align:right" , 58 , style="text-align:right" , 79 , 136.907806(14) , 9.0(3) h , β⁺ , ¹³⁷La , 3/2+ , , , - , rowspan=2 style="text-indent:1em" , ^137mCe , rowspan=2 colspan="3" style="text-indent:2em" , 254.29(5) keV , rowspan=2, 34.4(3) h , IT (99.22%) , ¹³⁷Ce , rowspan=2, 11/2− , rowspan=2, , rowspan=2, , - , β⁺ (.779%) , ¹³⁷La , - , ¹³⁸Ce , style="text-align:right" , 58 , style="text-align:right" , 80 , 137.905991(11) , colspan=3 align=center, Observationally StableTheorized to undergo β⁺β⁺ decay to ¹³⁸Ba with a half-life over 150×10¹² years , 0+ , 0.00251(2) , 0.00251–0.00254 , - , style="text-indent:1em" , ^138mCe , colspan="3" style="text-indent:2em" , 2129.17(12) keV , 8.65(20) ms , IT , ¹³⁸Ce , 7- , , , - , ¹³⁹Ce , style="text-align:right" , 58 , style="text-align:right" , 81 , 138.906653(8) , 137.641(20) d , EC , ¹³⁹La , 3/2+ , , , - , style="text-indent:1em" , ^139mCe , colspan="3" style="text-indent:2em" , 754.24(8) keV , 56.54(13) s , IT , ¹³⁹Ce , 11/2− , , , - , ¹⁴⁰Ce Fission product , style="text-align:right" , 58 , style="text-align:right" , 82 , 139.9054387(26) , colspan=3 align=center, StableTheoretically capable of spontaneous fission , 0+ , 0.88450(51) , 0.88446–0.88449 , - , style="text-indent:1em" , ^140mCe , colspan="3" style="text-indent:2em" , 2107.85(3) keV , 7.3(15) µs , , , 6+ , , , - , ¹⁴¹Ce , style="text-align:right" , 58 , style="text-align:right" , 83 , 140.9082763(26) , 32.508(13) d , β⁻ , ¹⁴¹Pr , 7/2− , , , - , ¹⁴²Ce , style="text-align:right" , 58 , style="text-align:right" , 84 , 141.909244(3) , colspan=3 align=center, Observationally Stable , 0+ , 0.11114(51) , 0.11114–0.11114 , - , ¹⁴³Ce , style="text-align:right" , 58 , style="text-align:right" , 85 , 142.912386(3) , 33.039(6) h , β⁻ , ¹⁴³Pr , 3/2− , , , - , ¹⁴⁴Ce , style="text-align:right" , 58 , style="text-align:right" , 86 , 143.913647(4) , 284.91(5) d , β⁻ , ^144mPr , 0+ , , , - , ¹⁴⁵Ce , style="text-align:right" , 58 , style="text-align:right" , 87 , 144.91723(4) , 3.01(6) min , β⁻ , ¹⁴⁵Pr , (3/2−) , , , - , ¹⁴⁶Ce , style="text-align:right" , 58 , style="text-align:right" , 88 , 145.91876(7) , 13.52(13) min , β⁻ , ¹⁴⁶Pr , 0+ , , , - , ¹⁴⁷Ce , style="text-align:right" , 58 , style="text-align:right" , 89 , 146.92267(3) , 56.4(10) s , β⁻ , ¹⁴⁷Pr , (5/2−) , , , - , ¹⁴⁸Ce , style="text-align:right" , 58 , style="text-align:right" , 90 , 147.92443(3) , 56(1) s , β⁻ , ¹⁴⁸Pr , 0+ , , , - , ¹⁴⁹Ce , style="text-align:right" , 58 , style="text-align:right" , 91 , 148.9284(1) , 5.3(2) s , β⁻ , ¹⁴⁹Pr , (3/2−)# , , , - , ¹⁵⁰Ce , style="text-align:right" , 58 , style="text-align:right" , 92 , 149.93041(5) , 4.0(6) s , β⁻ , ¹⁵⁰Pr , 0+ , , , - , ¹⁵¹Ce , style="text-align:right" , 58 , style="text-align:right" , 93 , 150.93398(11) , 1.02(6) s , β⁻ , ¹⁵¹Pr , 3/2−# , , , - , ¹⁵²Ce , style="text-align:right" , 58 , style="text-align:right" , 94 , 151.93654(21)# , 1.4(2) s , β⁻ , ¹⁵²Pr , 0+ , , , - , ¹⁵³Ce , style="text-align:right" , 58 , style="text-align:right" , 95 , 152.94058(43)# , 500# ms 300 ns, β⁻ , ¹⁵³Pr , 3/2−# , , , - , ¹⁵⁴Ce , style="text-align:right" , 58 , style="text-align:right" , 96 , 153.94342(54)# , 300# ms 300 ns, β⁻ , ¹⁵⁴Pr , 0+ , , , - , ¹⁵⁵Ce , style="text-align:right" , 58 , style="text-align:right" , 97 , 154.94804(64)# , 200# ms 300 ns, β⁻ , ¹⁵⁵Pr , 5/2−# , , , - , ¹⁵⁶Ce , style="text-align:right" , 58 , style="text-align:right" , 98 , 155.95126(64)# , 150# ms , β⁻ , ¹⁵⁶Pr , 0+ , , , - , ¹⁵⁷Ce , style="text-align:right" , 58 , style="text-align:right" , 99 , 156.95634(75)# , 50# ms , β⁻ , ¹⁵⁷Pr , 7/2+# , ,

References

* Isotope masses from: ** * Isotopic compositions and standard atomic masses from: ** ** * Half-life, spin, and isomer data selected from the following sources. ** ** ** {{Authority control Cerium

Cerium Cerium is a chemical element with the symbol Ce and atomic number 58. Cerium is a soft, ductile, and silvery-white metal that tarnishes when exposed to air. Cerium is the second element in the lanthanide series, and while it often shows the +3 ...