Isotopes of curium

Main isotopes of Chemistry:curium (96Cm) | Iso­tope | Decay

|

| abun­dance | half-life (t1/2) | mode | pro­duct
242Cm  | syn | 160 d  | α | 238Pu
SF | –
243Cm  | syn  | 29.1 y | α  | 239Pu
ε | 243Am
SF  | –
244Cm  | syn  | 18.1 y  | α  | 240Pu
SF  | –
245Cm  | syn  | 8500 y  | α  | 241Pu
SF  | –
246Cm  | syn  | 4730 y  | α  | 242Pu
SF  | –
247Cm  | syn  | 1.56×107 y | α  | 243Pu
248Cm  | syn  | 3.40×105 y | α  | 244Pu
SF  | –
250Cm  | syn  | 9000 y  | SF  | –
α  | 246Pu
β− | 250Bk
view * talk * edit

Curium (96Cm) is an artificial element with an atomic number of 96. Because it is an artificial element, a standard atomic weight cannot be given, and it has no stable isotopes. The first isotope synthesized was 242Cm in 1944, which has 146 neutrons.

There are 19 known radioisotopes ranging from 233Cm to 251Cm. There are also ten known nuclear isomers. The longest-lived isotope is 247Cm, with half-life 15.6 million years – orders of magnitude longer than that of any known isotope beyond curium, and long enough to study as a possible extinct radionuclide that would be produced by the r-process.[1][2] It is followed by 248Cm, which has a half-life of 348,000 years. The longest-lived known isomer is 246mCm with a half-life of 1.12 seconds.

## List of isotopes

Nuclide
[n 1] | Z | N | Isotopic mass (u)
[n 2][n 3] | Half-life
[n 4] | Decay
mode
[n 5] | Daughter
isotope
| Spin and
parity
[n 6][n 4]

|
|
|
|
|
|
|

Excitation energy[n 4]
233Cm  | 96  | 137  | 233.05077(9)  | 2010 | 27(10) s | β+ (80%)  | 233Am  | 3/2+#
α (20%)  | 229Pu
234Cm  | 96  | 138  | 234.050159(18)  | 2016 | 52(9) s | β+ (71%)  | 234Am  | 0+
α (27%)  | 230Pu
SF (2%)  | (various)
235Cm  | 96  | 139  | 235.05155(11)#  | 2020 | 7(3) min | β+? (96%)  | 235Am  | 5/2+#
α (4%)  | 231Pu
236Cm  | 96  | 140  | 236.051372(19)  | 2010 | 6.8(8) min | β+ (82%)  | 236Am  | 0+
α (18%)  | 232Pu
237Cm  | 96  | 141  | 237.05287(8)  | 2002 | >10# min  | α (?%)  | 233Pu  | 5/2+#
238Cm  | 96  | 142  | 238.053082(13)  | 1994 | 2.2(4) h | EC? (96.11%)  | 238Am  | 0+
α (3.84%)  | 234Pu
SF (0.048%)  | (various)
239Cm  | 96  | 143  | 239.05491(16)  | 2008 | 2.5(4) h | β+ | 239Am  | 7/2−#
α (6.2x10−3%)  | 235Pu
240Cm  | 96  | 144  | 240.0555282(20)  | 1949 | 30.4(37) d | α  | 236Pu  | 0+
SF (3.9×10−6%)  | (various)
241Cm  | 96  | 145  | 241.0576512(17)  | 1952 | 32.8(2) d | EC (99.0%)  | 241Am  | 1/2+
α (1.0%)  | 237Pu
242Cm  | 96  | 146  | 242.0588342(12)  | 1949 | 162.8(2) d | α[n 7] | 238Pu  | 0+
SF (6.2×10−6%)  | (various)
CD (1.1×10−14%)[n 8] | 208Pb
34Si
242mCm  | 2800(100) keV  | 1971 | 180(70) ns | SF?  | (various)  |
IT?  | 242Cm
243Cm  | 96  | 147  | 243.0613873(16)  | 1950 | 29.1(1) y | α (99.71%)  | 239Pu  | 5/2+
EC (0.29%)  | 243Am
SF (5.3×10−9%)  | (various)
243mCm  | 87.4(1) keV  | 1975 | 1.08(3) μs | IT  | 243Cm  | 1/2+
244Cm  | 96  | 148  | 244.0627506(12)  | 1950 | 18.11(3) y | α  | 240Pu  | 0+
SF (1.37×10−4%)  | (various)
244m1Cm  | 1040.181(11) keV  | 1963 | 34(2) ms | IT  | 244Cm  | 6+
244m2Cm  | 1100(900)# xkeV  | (1969)[n 9] | >500 ns  | SF  | (various)  |
245Cm  | 96  | 149  | 245.0654910(12)  | 1954 | 8250(70) y | α  | 241Pu  | 7/2+
SF (6.1×10−7%)  | (various)
245mCm  | 355.92(10) keV  | 1975 | 290(20) ns | IT  | 245Cm  | 1/2+
246Cm  | 96  | 150  | 246.0672220(16)  | 1954 | 4706(40) y | α (99.97%)  | 242Pu  | 0+
SF (0.02615%)  | (various)
246mCm  | 1179.66(13) keV  | 2008 | 1.12(24) s | IT  | 246Cm  | 8−
247Cm  | 96  | 151  | 247.070353(4)  | 1954 | 1.56(5)×107 y | α[n 10] | 243Pu  | 9/2−
247m1Cm  | 227.38(19) keV  | 1968 | 26.3(3) μs | IT  | 247Cm  | 5/2+
247m2Cm  | 404.90(3) keV  | 2003 | 100.6(6) ns | IT  | 247Cm  | 1/2+
248Cm  | 96  | 152  | 248.0723491(25)  | 1956 | 3.48(6)×105 y | α (91.61%)[n 11] | 244Pu  | 0+
SF (8.39%)  | (various)
248mCm  | 1458.1(10) keV  | 2019 | 146(18) μs | IT  | 248Cm  | 8−#
249Cm  | 96  | 153  | 249.0759540(25)  | 1956 | 64.15(3) min | β− | 249Bk  | 1/2+
249mCm  | 48.76(4) keV  | (1966)[n 12] | 23 μs |  |  | 7/2+
250Cm  | 96  | 154  | 250.078358(11)  | 1966 | 8300# y[n 13] | SF[n 14] | (various)  | 0+
α (?%)  | 246Pu
β− (?%)  | 250Bk
251Cm  | 96  | 155  | 251.082285(24)  | 1978 | 16.8(2) min | β− | 251Bk  | (3/2+)

1. ↑ mCm - 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. ↑ 4.0 4.1 4.2 # - Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
5. ↑ Modes of decay:  CD: | Cluster decay

|

EC: | Electron capture
SF: | Spontaneous fission
6. ↑ ( ) spin value - Indicates spin with weak assignment arguments.
7. ↑ Theoretically capable of β+β+ decay to 242Pu
8. ↑ Heaviest known nuclide to undergo cluster decay
9. ↑ Only published in a conference proceeding and not a refereed journal
10. ↑ Theoretically capable of β− decay to 247Bk or SF
11. ↑ Theoretically capable of β−β− decay to 248Cf
12. ↑ Only quoted from a private communication and not a refereed journal
13. ↑ Only SF has been observed with a half-life 11,300 years; the value given theoretically estimates alpha- and beta-decay branches, which is quite uncertain.[3]
14. ↑ The nuclide with the lowest atomic number known (almost surely) to undergo spontaneous fission as the main decay mode

## Actinides vs fission products

Actinides and fission products by half-life v * d * e

Actinides[4] by decay chain | Half-life
range (y)  | Fission products of 235U by yield<ref>Specifically from thermal neutron fission of U-235, e.g. in a typical nuclear reactor.</ref>
4n | 4n+1 | 4n+2 | 4n+3
| 4.5–7%  | 0.04–1.25%  | <0.001%
228Ra№ |  |  |  | 4–6  | †  |  | 155Euþ |
244Cmƒ | 241Puƒ | 250Cf  | 227Ac№ | 10–29  | 90Sr  | 85Kr  | 113mCdþ
232Uƒ |  | 238Puƒ | 243Cmƒ | 29–97  | 137Cs  | 151Smþ | 121mSn
248Bk[5] | 249Cfƒ | 242mAmƒ |  | 141–351  |

No fission products
have a half-life
in the range of
100–210 k years ...

| 241Amƒ |  | 251Cfƒ[6] | 430–900
|  | 226Ra№ | 247Bk  | 1.3 k – 1.6 k
240Pu  | 229Th  | 246Cmƒ | 243Amƒ | 4.7 k – 7.4 k
| 245Cmƒ | 250Cm  |  | 8.3 k – 8.5 k
|  |  | 239Puƒ | 24.1 k
|  | 230Th№ | 231Pa№ | 32 k – 76 k
236Npƒ | 233Uƒ | 234U№ |  | 150 k – 250 k  | ‡  | 99Tc₡ | 126Sn
248Cm  |  | 242Pu  |  | 327 k – 375 k  |  | 79Se₡
|  |  |  | 1.53 M  | 93Zr
| 237Npƒ |  |  | 2.1 M – 6.5 M  | 135Cs₡ | 107Pd
236U  |  |  | 247Cmƒ | 15 M – 24 M  |  | 129I₡
244Pu  |  |  |  | 80 M  |

... nor beyond 15.7 M years[7]

232Th№ |  | 238U№ | 235Uƒ№ | 0.7 G – 14.1 G

Legend for superscript symbols
₡ has thermal neutron capture cross section in the range of 8–50 barns
ƒ fissile
m metastable isomer
№ primarily a naturally occurring radioactive material (NORM)
þ neutron poison (thermal neutron capture cross section greater than 3k barns)
† range 4–97 y: Medium-lived fission product
‡ over 200,000 y: Long-lived fission product

## References

1. ↑ Côté, Benoit; Eichler, Marius; Yagüe López, Andrés; Vassh, Nicole; Mumpower, Matthew R.; Világos, Blanka; Soós, Benjámin; Arcones, Almudena et al. (26 February 2021). "129I and 247Cm in meteorites constrain the last astrophysical source of solar r-process elements". Science 371 (6532): 945–948. doi:10.1126/science.aba1111. PMID 33632846. Bibcode: 2021Sci...371..945C.
2. ↑ Davis, A.M.; McKeegan, K.D. (2014). "Short-Lived Radionuclides and Early Solar System Chronology". Treatise on Geochemistry: 383. doi:10.1016/B978-0-08-095975-7.00113-3. ISBN 9780080983004.
3. ↑ "Adopted Levels for 250Cm". NNDC Chart of Nuclides. https://www.nndc.bnl.gov/ensnds/250/Cm/adopted.pdf.
4. ↑ Plus radium (element 88). While actually a sub-actinide, it immediately precedes actinium (89) and follows a three-element gap of instability after polonium (84) where no nuclides have half-lives of at least four years (the longest-lived nuclide in the gap is radon-222 with a half life of less than four days). Radium's longest lived isotope, at 1,600 years, thus merits the element's inclusion here.
5. ↑ Milsted, J.; Friedman, A. M.; Stevens, C. M. (1965). "The alpha half-life of berkelium-247; a new long-lived isomer of berkelium-248". Nuclear Physics 71 (2): 299. doi:10.1016/0029-5582(65)90719-4. Bibcode: 1965NucPh..71..299M.
"The isotopic analyses disclosed a species of mass 248 in constant abundance in three samples analysed over a period of about 10 months. This was ascribed to an isomer of Bk248 with a half-life greater than 9 y. No growth of Cf248 was detected, and a lower limit for the β− half-life can be set at about 104 y. No alpha activity attributable to the new isomer has been detected; the alpha half-life is probably greater than 300 y."
6. ↑ This is the heaviest nuclide with a half-life of at least four years before the "Sea of Instability".
7. ↑ Excluding those "classically stable" nuclides with half-lives significantly in excess of 232Th; e.g., while 113mCd has a half-life of only fourteen years, that of 113Cd is nearly eight quadrillion years.

* Isotope masses from:
* Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A 729: 3–128, doi:10.1016/j.nuclphysa.2003.11.001, Bibcode: 2003NuPhA.729....3A, https://hal.archives-ouvertes.fr/in2p3-00020241/document
* Half-life, spin, and isomer data selected from the following sources.
* Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A 729: 3–128, doi:10.1016/j.nuclphysa.2003.11.001, Bibcode: 2003NuPhA.729....3A, https://hal.archives-ouvertes.fr/in2p3-00020241/document
* National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory. http://www.nndc.bnl.gov/nudat2/.
* Lide, David R., ed (2004). "11. Table of the Isotopes". CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.

* v
* t
* e

Isotopes of the chemical elements

| Group | 1 | 2 | 3 |  | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18

|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|

Period | Alkali metals  | Alkaline earth metals  |  |  |  |  |  |  |  |  |  |  |  |  |  | Pnicto­gens  | Chal­co­gens  | Halo­gens  | Noble gases
1 |

Iso's * List

1  |  |

Iso's * List

2 |

Iso's * List

3  |

Iso's * List

4  |  |

Iso's * List

5  |

Iso's * List

6  |

Iso's * List

7  |

Iso's * List

8  |

Iso's * List

9  |

Iso's * List

3 |

Iso's * List

11  |

Iso's * List

12  |  |

Iso's * List

13  |

Iso's * List

14  |

Iso's * List

15  |

Iso's * List

16  |

Iso's * List

17  |

Iso's * List

4 |

Iso's * List

19  |

Iso's * List

20  |

Iso's * List

21  |  |

Iso's * List

22  |

Iso's * List

23  |

Iso's * List

24  |

Iso's * List

25  |

Iso's * List

26  |

Iso's * List

27  |

Iso's * List

28  |

Iso's * List

29  |

Iso's * List

30  |

Iso's * List

31  |

Iso's * List

32  |

Iso's * List

33  |

Iso's * List

34  |

Iso's * List

35  |

Iso's * List

5 |

Iso's * List

37  |

Iso's * List

38  |

Iso's * List

39  |  |

Iso's * List

40  |

Iso's * List

41  |

Iso's * List

42  |

Iso's * List

43  |

Iso's * List

44  |

Iso's * List

45  |

Iso's * List

46  |

Iso's * List

47  |

Iso's * List

48  |

Iso's * List

49  |

Iso's * List

50  |

Iso's * List

51  |

Iso's * List

52  |

Iso's * List

53  |

Iso's * List

6 |

Iso's * List

55  |

Iso's * List

56  |

Iso's * List

57  |  |

Iso's * List

72  |

Iso's * List

73  |

Iso's * List

74  |

Iso's * List

75  |

Iso's * List

76  |

Iso's * List

77  |

Iso's * List

78  |

Iso's * List

79  |

Iso's * List

80  |

Iso's * List

81  |

Iso's * List

82  |

Iso's * List

83  |

Iso's * List

84  |

Iso's * List

85  |

Iso's * List

7 |

Iso's * List

87  |

Iso's * List

88  |

Iso's * List

89  |  |

Iso's * List

104  |

Iso's * List

105  |

Iso's * List

106  |

Iso's * List

107  |

Iso's * List

108  |

Iso's * List

109  |

Iso's * List

110  |

Iso's * List

111  |

Iso's * List

112  |

Iso's * List

113  |

Iso's * List

114  |

Iso's * List

115  |

Iso's * List

116  |

Iso's * List

117  |

Iso's * List

118
|  |  |  |  |

Iso's * List

58  |

Iso's * List

59  |

Iso's * List

60  |

Iso's * List

61  |

Iso's * List

62  |

Iso's * List

63  |

Iso's * List

64  |

Iso's * List

65  |

Iso's * List

66  |

Iso's * List

67  |

Iso's * List

68  |

Iso's * List

69  |

Iso's * List

70  |

Iso's * List

71  |
|  |

Iso's * List

90  |

Iso's * List

91  |

Iso's * List

92  |

Iso's * List

93  |

Iso's * List

94  |

Iso's * List

95  |

Iso's * List

96  |

Iso's * List

97  |

Iso's * List

98  |

Iso's * List

99  |

Iso's * List

100  |

Iso's * List

101  |

Iso's * List

102  |

Iso's * List

103

* Table of nuclides
* Categories: Isotopes
* Tables of nuclides
* Metastable isotopes
* Isotopes by element

0.00

(0 votes)

Original source: https://en.wikipedia.org/wiki/Isotopes of curium. Read more

|

Retrieved from "https://handwiki.org/wiki/index.php?title=Physics:Isotopes_of_curium&oldid=4367898"
*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template