# Isotopes of cerium

Naturally occurring cerium ($_{58}$Ce) is composed of 4 stable isotopes: $^{136}$Ce, $^{138}$Ce, $^{140}$Ce, and $^{142}$Ce, with $^{140}$Ce being the most abundant (88.48% natural abundance) and the only one theoretically stable; $^{136}$Ce, $^{138}$Ce, and $^{142}$Ce 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 $^{144}$Ce, with a half-life of 284.893 days; $^{139}$Ce, with a half-life of 137.640 days and $^{141}$Ce, 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 ($^{119}$Ce) to 157 u ($^{157}$Ce).

## List of isotopes

| Nuclide | Z | N | Isotopic mass (Da) | Half-life | Decay mode | Daughter isotope | Spin and parity | Natural abundance (mole fraction) | Natural abundance (mole fraction) |
| Nuclide | Excitation energy | Excitation energy | Excitation energy | Half-life | Decay mode | Daughter isotope | Spin and parity | Normal proportion | Range of variation |
| $^{121}$Ce | 58 | 63 | 120.94344(43)# | 1.1(1) s | β$^+$ (99%) | $^{121}$La | 5/2(+#) | | |
| $^{121}$Ce | 58 | 63 | 120.94344(43)# | 1.1(1) s | β$^+$, p (1%) | $^{120}$Ba | 5/2(+#) | | |
| $^{122}$Ce | 58 | 64 | 121.93787(43)# | 2# s | β$^+$ | $^{122}$La | 0+ | | |
| $^{123}$Ce | 58 | 65 | 122.93528(32)# | 3.8(2) s | β$^+$ (?%) | $^{123}$La | (5/2)(+#) | | |
| $^{123}$Ce | 58 | 65 | 122.93528(32)# | 3.8(2) s | β$^+$, p (?%) | $^{122}$Ba | (5/2)(+#) | | |
| $^{124}$Ce | 58 | 66 | 123.93031(32)# | 9.1(12) s | β$^+$ | $^{124}$La | 0+ | | |
| $^{125}$Ce | 58 | 67 | 124.92844(21)# | 9.7(3) s | β$^+$ (?%) | $^{125}$La | (7/2−) | | |
| $^{125}$Ce | 58 | 67 | 124.92844(21)# | 9.7(3) s | β$^+$, p (?%) | $^{124}$Ba | (7/2−) | | |
| $^{125m}$Ce | 93.6(4) keV | 93.6(4) keV | 93.6(4) keV | 13(10) s | IT | $^{125}$Ce | (1/2+) | | |
| $^{126}$Ce | 58 | 68 | 125.923971(30) | 51.0(3) s | β$^+$ | $^{126}$La | 0+ | | |
| $^{127}$Ce | 58 | 69 | 126.922727(31) | 34(2) s | β$^+$ | $^{127}$La | (1/2+) | | |
| $^{127m1}$Ce | 7.3(11) keV | 7.3(11) keV | 7.3(11) keV | 28.6(7) s | β$^+$ | $^{127}$La | (5/2+) | | |
| $^{127m2}$Ce | 36.9(11) keV | 36.9(11) keV | 36.9(11) keV | >10 μs | IT | $^{127}$Ce | (7/2−) | | |
| $^{128}$Ce | 58 | 70 | 127.918911(30) | 3.93(2) min | β$^+$ | $^{128}$La | 0+ | | |
| $^{129}$Ce | 58 | 71 | 128.918102(30) | 3.5(3) min | β$^+$ | $^{129}$La | (5/2+) | | |
| $^{130}$Ce | 58 | 72 | 129.914736(30) | 22.9(5) min | β$^+$ | $^{130}$La | 0+ | | |
| $^{130m}$Ce | 2453.6(3) keV | 2453.6(3) keV | 2453.6(3) keV | 100(8) ns | IT | $^{130}$Ce | 7− | | |
| $^{131}$Ce | 58 | 73 | 130.914429(35) | 10.3(3) min | β$^+$ | $^{131}$La | 7/2+ | | |
| $^{131m}$Ce | 63.09(9) keV | 63.09(9) keV | 63.09(9) keV | 5.4(4) min | β$^+$ | $^{131}$La | (1/2+) | | |
| $^{132}$Ce | 58 | 74 | 131.911466(22) | 3.51(11) h | β$^+$ | $^{132}$La | 0+ | | |
| $^{132m}$Ce | 2341.15(21) keV | 2341.15(21) keV | 2341.15(21) keV | 9.4(3) ms | IT | $^{132}$Ce | 8− | | |
| $^{133}$Ce | 58 | 75 | 132.911520(18) | 97(4) min | β$^+$ | $^{133}$La | 1/2+ | | |
| $^{133m}$Ce | 37.2(7) keV | 37.2(7) keV | 37.2(7) keV | 5.1(3) h | β$^+$ | $^{133}$La | 9/2− | | |
| $^{134}$Ce | 58 | 76 | 133.908928(22) | 3.16(4) d | EC | $^{134}$La | 0+ | | |
| $^{134m}$Ce | 3208.6(4) keV | 3208.6(4) keV | 3208.6(4) keV | 308(5) ns | IT | $^{134}$Ce | 10+ | | |
| $^{135}$Ce | 58 | 77 | 134.909161(11) | 17.7(3) h | β$^+$ | $^{135}$La | 1/2+ | | |
| $^{135m}$Ce | 445.81(21) keV | 445.81(21) keV | 445.81(21) keV | 20(1) s | IT | $^{135}$Ce | (11/2−) | | |
| $^{136}$Ce | 58 | 78 | 135.90712926(35) | Observationally Stable | Observationally Stable | Observationally Stable | 0+ | 0.00186(2) | |
| $^{136m}$Ce | 3095.0(6) keV | 3095.0(6) keV | 3095.0(6) keV | 1.96(9) μs | IT | $^{136}$Ce | 10+ | | |
| $^{137}$Ce | 58 | 79 | 136.90776242(39) | 9.0(3) h | β$^+$ | $^{137}$La | 3/2+ | | |
| $^{137m}$Ce | 254.29(5) keV | 254.29(5) keV | 254.29(5) keV | 34.4(3) h | IT (99.21%) | $^{137}$Ce | 11/2− | | |
| $^{137m}$Ce | 254.29(5) keV | 254.29(5) keV | 254.29(5) keV | 34.4(3) h | β$^+$ (0.79%) | $^{137}$La | 11/2− | | |
| $^{138}$Ce | 58 | 80 | 137.90599418(54) | Observationally Stable | Observationally Stable | Observationally Stable | 0+ | 0.00251(2) | |
| $^{138m}$Ce | 2129.28(12) keV | 2129.28(12) keV | 2129.28(12) keV | 8.73(20) ms | IT | $^{138}$Ce | 7- | | |
| $^{139}$Ce | 58 | 81 | 138.9066470(22) | 137.642(20) d | EC | $^{139}$La | 3/2+ | | |
| $^{139m}$Ce | 754.24(8) keV | 754.24(8) keV | 754.24(8) keV | 57.58(32) s | IT | $^{139}$Ce | 11/2− | | |
| $^{140}$Ce | 58 | 82 | 139.9054484(14) | Stable | Stable | Stable | 0+ | 0.88449(51) | |
| $^{140m}$Ce | 2107.854(24) keV | 2107.854(24) keV | 2107.854(24) keV | 7.3(15) μs | IT | $^{140}$Ce | 6+ | | |
| $^{141}$Ce | 58 | 83 | 140.9082860(14) | 32.505(10) d | β$^−$ | $^{141}$Pr | 7/2− | | |
| $^{142}$Ce | 58 | 84 | 141.9092502(26) | Observationally Stable | Observationally Stable | Observationally Stable | 0+ | 0.11114(51) | |
| $^{143}$Ce | 58 | 85 | 142.9123920(26) | 33.039(6) h | β$^−$ | $^{143}$Pr | 3/2− | | |
| $^{144}$Ce | 58 | 86 | 143.9136528(30) | 284.886(25) d | β$^−$ | $^{144}$Pr | 0+ | | |
| $^{145}$Ce | 58 | 87 | 144.917265(36) | 3.01(6) min | β$^−$ | $^{145}$Pr | 5/2−# | | |
| $^{146}$Ce | 58 | 88 | 145.918812(16) | 13.49(16) min | β$^−$ | $^{146}$Pr | 0+ | | |
| $^{147}$Ce | 58 | 89 | 146.9226899(92) | 56.4(10) s | β$^−$ | $^{147}$Pr | (5/2−) | | |
| $^{148}$Ce | 58 | 90 | 147.924424(12) | 56.8(3) s | β$^−$ | $^{148}$Pr | 0+ | | |
| $^{149}$Ce | 58 | 91 | 148.928427(11) | 4.94(4) s | β$^−$ | $^{149}$Pr | 3/2−# | | |
| $^{150}$Ce | 58 | 92 | 149.930384(13) | 6.05(7) s | β$^−$ | $^{150}$Pr | 0+ | | |
| $^{151}$Ce | 58 | 93 | 150.934272(19) | 1.76(6) s | β$^−$ | $^{151}$Pr | (3/2−) | | |
| $^{152}$Ce | 58 | 94 | 151.93668(22)# | 1.42(2) s | β$^−$ | $^{152}$Pr | 0+ | | |
| $^{153}$Ce | 58 | 95 | 152.94105(22)# | 865(25) ms | β$^−$ | $^{153}$Pr | 3/2−# | | |
| $^{154}$Ce | 58 | 96 | 153.94394(22)# | 722(14) ms | β$^−$ | $^{154}$Pr | 0+ | | |
| $^{155}$Ce | 58 | 97 | 154.94871(32)# | 313(7) ms | β$^−$ | $^{155}$Pr | 5/2−# | | |
| $^{156}$Ce | 58 | 98 | 155.95188(32)# | 233(9) ms | β$^−$ | $^{156}$Pr | 0+ | | |
| $^{157}$Ce | 58 | 99 | 156.95713(43)# | 175(41) ms | β$^−$ | $^{157}$Pr | 7/2+# | | |
| $^{158}$Ce | 58 | 100 | 157.96077(43)# | 99(93) ms | β$^−$ | $^{158}$Pr | 0+ | | |
| This table header & footer: view ||||||||||
* ↑ $^m$Ce – Excited nuclear isomer.
* ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
* ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
* 1 2 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
* ↑ Modes of decay: EC:Electron capture IT:Isomeric transition p:Proton emission
* ↑ Bold symbol as daughter – Daughter product is stable.
* ↑ ( ) spin value – Indicates spin with weak assignment arguments.
* ↑ Theorized to undergo β$^+$β$^+$ decay to $^{136}$Ba with a half-life over 3.2×10$^{16}$ years
* ↑ Theorized to undergo β$^+$β$^+$ decay to $^{138}$Ba with a half-life over 4.4×10$^{16}$ years
* 1 2 3 4 5 Fission product
* ↑ Theorized to undergo β$^−$β$^−$ decay to $^{142}$Nd or α decay to $^{138}$Ba with a half-life over 2.9×10$^{18}$ years