Naturally occurring cerium (₅₈Ce) is composed of 4 stable isotopes: ¹³⁶Ce, ¹³⁸Ce, ¹⁴⁰Ce, and ¹⁴²Ce, with ¹⁴⁰Ce being the most abundant (88.48% natural abundance) and the only one theoretically stable; ¹³⁶Ce, ¹³⁸Ce, and ¹⁴²Ce are predicted to undergo double beta decay but this process has never been observed. There are 35 radioisotopes 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 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 states. The isotopes of cerium range in atomic weight 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 StableTheorized to undergo β⁺β⁺ decay to ¹³⁶Ba with a half-life 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 Nuclear fission products are the atomic fragments left after a large atomic nucleus undergoes nuclear fission. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons, the release ...

, style="text-align:right" , 58 , style="text-align:right" , 82 , 139.9054387(26) , colspan=3 align=center, StableTheoretically capable of

spontaneous fission Spontaneous fission (SF) is a form of radioactive decay that is found only in very heavy chemical elements. The nuclear binding energy of the elements reaches its maximum at an atomic mass number of about 56 (e.g., iron-56); spontaneous breakdo ...

, 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