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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.

Main isotopes of cerium (58Ce)
Iso­tope Decay
abun­dance half-life (t1/2) mode pro­duct
134Ce syn 3.16 d ε 134La
136Ce 0.186% stable
138Ce 0.251% stable
139Ce syn 137.640 d ε 139La
140Ce 88.449% stable
141Ce syn 32.501 d β 141Pr
142Ce 11.114% stable
143Ce syn 33.039 d β 143Pr
144Ce syn 284.893 d β 144Pr
Standard atomic weight Ar, standard(Ce)

The isotopes of cerium range in atomic weight from 119 u (119Ce) to 157 u (157Ce).

List of isotopesEdit

Nuclide
[n 1]
Z N Isotopic mass (u)
[n 2][n 3]
Half-life
[n 4]
Decay
mode

[n 5]
Daughter
isotope

[n 6]
Spin and
parity
[n 7][n 4]
Natural abundance (mole fraction)
Excitation energy Normal proportion Range of variation
119Ce 58 61 118.95276(64)# 200# ms β+ 119La 5/2+#
120Ce 58 62 119.94664(75)# 250# ms β+ 120La 0+
121Ce 58 63 120.94342(54)# 1.1(1) s β+ 121La (5/2)(+#)
122Ce 58 64 121.93791(43)# 2# s β+ 122La 0+
β+, p 121Ba
123Ce 58 65 122.93540(32)# 3.8(2) s β+ 123La (5/2)(+#)
β+, p 122Ba
124Ce 58 66 123.93041(32)# 9.1(12) s β+ 124La 0+
125Ce 58 67 124.92844(21)# 9.3(3) s β+ 125La (7/2−)
β+, p 124Ba
126Ce 58 68 125.92397(3) 51.0(3) s β+ 126La 0+
127Ce 58 69 126.92273(6) 29(2) s β+ 127La 5/2+#
128Ce 58 70 127.91891(3) 3.93(2) min β+ 128La 0+
129Ce 58 71 128.91810(3) 3.5(3) min β+ 129La (5/2+)
130Ce 58 72 129.91474(3) 22.9(5) min β+ 130La 0+
130mCe 2453.6(3) keV 100(8) ns (7−)
131Ce 58 73 130.91442(4) 10.2(3) min β+ 131La (7/2+)
131mCe 61.8(1) keV 5.0(10) min β+ 131La (1/2+)
132Ce 58 74 131.911460(22) 3.51(11) h β+ 132La 0+
132mCe 2340.8(5) keV 9.4(3) ms IT 132Ce (8−)
133Ce 58 75 132.911515(18) 97(4) min β+ 133La 1/2+
133mCe 37.1(8) keV 4.9(4) d β+ 133La 9/2−
134Ce 58 76 133.908925(22) 3.16(4) d EC 134La 0+
135Ce 58 77 134.909151(12) 17.7(3) h β+ 135La 1/2(+)
135mCe 445.8(2) keV 20(1) s IT 135Ce (11/2−)
136Ce 58 78 135.907172(14) Observationally Stable[n 8] 0+ 0.00185(2) 0.00185–0.00186
136mCe 3095.5(4) keV 2.2(2) µs 10+
137Ce 58 79 136.907806(14) 9.0(3) h β+ 137La 3/2+
137mCe 254.29(5) keV 34.4(3) h IT (99.22%) 137Ce 11/2−
β+ (.779%) 137La
138Ce 58 80 137.905991(11) Observationally Stable[n 9] 0+ 0.00251(2) 0.00251–0.00254
138mCe 2129.17(12) keV 8.65(20) ms IT 138Ce 7-
139Ce 58 81 138.906653(8) 137.641(20) d EC 139La 3/2+
139mCe 754.24(8) keV 56.54(13) s IT 139Ce 11/2−
140Ce[n 10] 58 82 139.9054387(26) Stable 0+ 0.88450(51) 0.88446–0.88449
140mCe 2107.85(3) keV 7.3(15) µs 6+
141Ce[n 10] 58 83 140.9082763(26) 32.508(13) d β 141Pr 7/2−
142Ce[n 10] 58 84 141.909244(3) Observationally Stable[n 11] 0+ 0.11114(51) 0.11114–0.11114
143Ce[n 10] 58 85 142.912386(3) 33.039(6) d β 143Pr 3/2−
144Ce[n 10] 58 86 143.913647(4) 284.91(5) d β 144mPr 0+
145Ce 58 87 144.91723(4) 3.01(6) min β 145Pr (3/2−)
146Ce 58 88 145.91876(7) 13.52(13) min β 146Pr 0+
147Ce 58 89 146.92267(3) 56.4(10) s β 147Pr (5/2−)
148Ce 58 90 147.92443(3) 56(1) s β 148Pr 0+
149Ce 58 91 148.9284(1) 5.3(2) s β 149Pr (3/2−)#
150Ce 58 92 149.93041(5) 4.0(6) s β 150Pr 0+
151Ce 58 93 150.93398(11) 1.02(6) s β 151Pr 3/2−#
152Ce 58 94 151.93654(21)# 1.4(2) s β 152Pr 0+
153Ce 58 95 152.94058(43)# 500# ms [>300 ns] β 153Pr 3/2−#
154Ce 58 96 153.94342(54)# 300# ms [>300 ns] β 154Pr 0+
155Ce 58 97 154.94804(64)# 200# ms [>300 ns] β 155Pr 5/2−#
156Ce 58 98 155.95126(64)# 150# ms β 156Pr 0+
157Ce 58 99 156.95634(75)# 50# ms β 157Pr 7/2+#
  1. ^ mCe – Excited nuclear isomer.
  2. ^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. ^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. ^ a b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  5. ^ Modes of decay:
    EC: Electron capture
    IT: Isomeric transition


    p: Proton emission
  6. ^ Bold symbol as daughter – Daughter product is stable.
  7. ^ ( ) spin value – Indicates spin with weak assignment arguments.
  8. ^ Theorized to undergo β+β+ decay to 136Ba with a half-life over 38×1015 years
  9. ^ Theorized to undergo β+β+ decay to 138Ba with a half-life over 150×1012 years
  10. ^ a b c d e Fission product
  11. ^ Theorized to undergo ββ decay to 142Nd with a half-life over 50×1015 years

ReferencesEdit

  1. ^ Meija, Juris; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305.