Isotopes of curium
{{Short description|Artificial nuclides with atomic number of 96 but with different mass numbers}}
{{Infobox curium isotopes}}
Curium ({{sub|96}}Cm) 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 {{sup|242}}Cm in 1944, which has 146 neutrons.
There are 19 known radioisotopes ranging from {{sup|233}}Cm to {{sup|251}}Cm. There are also ten known nuclear isomers. The longest-lived isotope is {{sup|247}}Cm, 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.{{cite journal |last1=Côté |first1=Benoit |last2=Eichler |first2=Marius |last3=Yagüe López |first3=Andrés |last4=Vassh |first4=Nicole |last5=Mumpower |first5=Matthew R. |last6=Világos |first6=Blanka |last7=Soós |first7=Benjámin |last8=Arcones |first8=Almudena|author8-link=Almudena Arcones |last9=Sprouse |first9=Trevor M. |last10=Surman |first10=Rebecca |last11=Pignatari |first11=Marco |last12=Pető |first12=Mária K. |last13=Wehmeyer |first13=Benjamin |last14=Rauscher |first14=Thomas |last15=Lugaro |first15=Maria |title=129I and 247Cm in meteorites constrain the last astrophysical source of solar r-process elements |journal=Science |date=26 February 2021 |volume=371 |issue=6532 |pages=945–948 |doi=10.1126/science.aba1111|pmid=33632846 |arxiv=2006.04833 |bibcode=2021Sci...371..945C |s2cid=232050526 }}{{cite journal |last1=Davis |first1=A.M. |last2=McKeegan |first2=K.D. |title=Short-Lived Radionuclides and Early Solar System Chronology |journal=Treatise on Geochemistry |date=2014 |page=383 |doi=10.1016/B978-0-08-095975-7.00113-3|isbn=9780080983004 }} The longest-lived known isomer is {{sup|246m}}Cm with a half-life of 1.12 seconds.
List of isotopes
{{Anchor|Curium-231|Curium-232|Curium-252}}
{{Isotopes table
|symbol=Cm
|refs=NUBASE2020, AME2020 II
|notes=m, unc(), hl#, mass#, exen#, spin(), spin#, SF, EC, CD,
}}
|-id=Curium-233
| rowspan=2|{{sup|233}}Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 137
| rowspan=2|233.050771(87)
| rowspan=2|27(10) s
| beta decay (80%)
| {{sup|233}}Am
| rowspan=2|3/2+#
|-
| α (20%)
| {{sup|229}}Pu
|-id=Curium-234
| rowspan=3|{{sup|234}}Cm
| rowspan=3 style="text-align:right" | 96
| rowspan=3 style="text-align:right" | 138
| rowspan=3|234.050159(18)
| rowspan=3|52(9) s
| β{{sup|+}} (71%)
| {{sup|234}}Am
| rowspan=3|0+
|-
| α (27%)
| {{sup|230}}Pu
|-
| SF (2%)
| (various)
|-id=Curium-235
| rowspan=2|{{sup|235}}Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 139
| rowspan=2|235.05155(11)#
| rowspan=2|7(3) min
| β{{sup|+}} (96%)
| {{sup|235}}Am
| rowspan=2|5/2+#
|-
| α (4%)
| {{sup|231}}Pu
|-id=Curium-236
| rowspan=2|{{sup|236}}Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 140
| rowspan=2|236.051372(19)
| rowspan=2|6.8(8) min
| β{{sup|+}} (82%)
| {{sup|236}}Am
| rowspan=2|0+
|-
| α (18%)
| {{sup|232}}Pu
|-id=Curium-237
| {{sup|237}}Cm
| style="text-align:right" | 96
| style="text-align:right" | 141
| 237.052869(80)
| >10# min
| α (?%)
| {{sup|233}}Pu
| 5/2+#
|-id=Curium-238
| rowspan=3|{{sup|238}}Cm
| rowspan=3 style="text-align:right" | 96
| rowspan=3 style="text-align:right" | 142
| rowspan=3|238.053082(13)
| rowspan=3|2.2(4) h
| EC (96.11%)
| {{sup|238}}Am
| rowspan=3|0+
|-
| α (3.84%)
| {{sup|234}}Pu
|-
| SF (0.048%)
| (various)
|-id=Curium-239
| rowspan=2|{{sup|239}}Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 143
| rowspan=2|239.05491(16)
| rowspan=2|2.5(4) h
| β{{sup|+}}
| {{sup|239}}Am
| rowspan=2|7/2−#
|-
| α (6.2x10{{sup|−3}}%)
| {{sup|235}}Pu
|-id=Curium-240
| rowspan=2|{{sup|240}}Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 144
| rowspan=2|240.0555282(20)
| rowspan=2|30.4(37) d
| α
| {{sup|236}}Pu
| rowspan=2|0+
|-
| SF (3.9×10{{sup|−6}}%)
| (various)
|-id=Curium-241
| rowspan=2|{{sup|241}}Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 145
| rowspan=2|241.0576512(17)
| rowspan=2|32.8(2) d
| EC (99.0%)
| {{sup|241}}Am
| rowspan=2|1/2+
|-
| α (1.0%)
| {{sup|237}}Pu
|-id=Curium-242
| rowspan=3|{{sup|242}}Cm
| rowspan=3 style="text-align:right" | 96
| rowspan=3 style="text-align:right" | 146
| rowspan=3|242.0588342(12)
| rowspan=3|162.8(2) d
| α{{refn|group=n|Theoretically capable of β{{sup|+}}β{{sup|+}} decay to {{sup|242}}Pu}}
| {{sup|238}}Pu
| rowspan=3|0+
|-
| SF (6.2×10{{sup|−6}}%)
| (various)
|-
| CD (1.1×10{{sup|−14}}%)Heaviest known nuclide to undergo cluster decay
| {{sup|208}}Pb
{{sup|34}}Si
|-id=Curium-242m
| style="text-indent:1em" | {{sup|242m}}Cm
| colspan="3" style="text-indent:2em" | 2800(100) keV
| 180(70) ns
|
|
|
|-id=Curium-243
| rowspan=3|{{sup|243}}Cm
| rowspan=3 style="text-align:right" | 96
| rowspan=3 style="text-align:right" | 147
| rowspan=3|243.0613873(16)
| rowspan=3|29.1(1) y
| α (99.71%)
| {{sup|239}}Pu
| rowspan=3|5/2+
|-
| EC (0.29%)
| {{sup|243}}Am
|-
| SF (5.3×10{{sup|−9}}%)
| (various)
|-id=Curium-243m
| style="text-indent:1em" | {{sup|243m}}Cm
| colspan="3" style="text-indent:2em" | 87.4(1) keV
| 1.08(3) μs
| IT
| {{sup|243}}Cm
| 1/2+
|-id=Curium-244
| rowspan=2|{{sup|244}}Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 148
| rowspan=2|244.0627506(12)
| rowspan=2|18.11(3) y
| α
| {{sup|240}}Pu
| rowspan=2|0+
|-
| SF (1.37×10{{sup|−4}}%)
| (various)
|-id=Curium-244m1
| style="text-indent:1em" | {{sup|244m1}}Cm
| colspan="3" style="text-indent:2em" | 1040.181(11) keV
| 34(2) ms
| IT
| {{sup|244}}Cm
| 6+
|-id=Curium-244m2
| style="text-indent:1em" | {{sup|244m2}}Cm
| colspan="3" style="text-indent:2em" | 1100(900)# keV
| >500 ns
| SF
| (various)
|
|-id=Curium-245
| rowspan=2|{{sup|245}}Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 149
| rowspan=2|245.0654910(12)
| rowspan=2|8250(70) y
| α
| {{sup|241}}Pu
| rowspan=2|7/2+
|-
| SF (6.1×10{{sup|−7}}%)
| (various)
|-id=Curium-245m
| style="text-indent:1em" | {{sup|245m}}Cm
| colspan="3" style="text-indent:2em" | 355.92(10) keV
| 290(20) ns
| IT
| {{sup|245}}Cm
| 1/2+
|-id=Curium-246
| rowspan=2|{{sup|246}}Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 150
| rowspan=2|246.0672220(16)
| rowspan=2|4706(40) y
| α (99.97%)
| {{sup|242}}Pu
| rowspan=2|0+
|-
| SF (0.02615%)
| (various
|-id=Curium-246m
| style="text-indent:1em" | {{sup|246m}}Cm
| colspan="3" style="text-indent:2em" | 1179.66(13) keV
| 1.12(24) s
| IT
| {{sup|246}}Cm
| 8−
|-id=Curium-247
| {{sup|247}}Cm
| style="text-align:right" | 96
| style="text-align:right" | 151
| 247.0703527(41)
| 1.56(5)×10{{sup|7}} y
| α
| {{sup|243}}Pu
| 9/2−
|-id=Curium-247m1
| style="text-indent:1em" | {{sup|247m1}}Cm
| colspan="3" style="text-indent:2em" | 227.38(19) keV
| 26.3(3) μs
| IT
| {{sup|247}}Cm
| 5/2+
|-id=Curium-247m2
| style="text-indent:1em" | {{sup|247m2}}Cm
| colspan="3" style="text-indent:2em" | 404.90(3) keV
| 100.6(6) ns
| IT
| {{sup|247}}Cm
| 1/2+
|-id=Curium-248
| rowspan=2|{{sup|248}}Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 152
| rowspan=2|248.0723491(25)
| rowspan=2|3.48(6)×10{{sup|5}} y
| α (91.61%){{refn|group=n|Theoretically capable of β{{sup|−}}β{{sup|−}} decay to {{sup|248}}Cf}}
| {{sup|244}}Pu
| rowspan=2|0+
|-
| SF (8.39%)
| (various)
|-id=Curium-248m
| style="text-indent:1em" | {{sup|248m}}Cm
| colspan="3" style="text-indent:2em" | 1458.1(10) keV
| 146(18) μs
| IT
| {{sup|248}}Cm
| 8−#
|-id=Curium-249
| {{sup|249}}Cm
| style="text-align:right" | 96
| style="text-align:right" | 153
| 249.0759540(25)
| 64.15(3) min
| β{{sup|−}}
| {{sup|249}}Bk
| 1/2+
|-id=Curium-249m
| style="text-indent:1em" | {{sup|249m}}Cm
| colspan="3" style="text-indent:2em" | 48.76(4) keV
| 23 μs
| α{{refn|group=n|Decay mode is uncertain due to disagreements between theoretical predictions and reported experimental data.}}
| {{sup|245}}Pu
| 7/2+
|-id=Curium-250
| rowspan=3|{{sup|250}}Cm
| rowspan=3 style="text-align:right" | 96
| rowspan=3 style="text-align:right" | 154
| rowspan=3|250.078358(11)
| rowspan=3|8300# y
| SF (74%)The nuclide with the lowest atomic number known to undergo spontaneous fission as the main decay mode
| (various)
| rowspan=3|0+
|-
| α (?%)
| {{sup|246}}Pu
|-
| β{{sup|−}} (?%)
| {{sup|250}}Bk
|-id=Curium-251
| {{sup|251}}Cm
| style="text-align:right" | 96
| style="text-align:right" | 155
| 251.082285(24)
| 16.8(2) min
| β{{sup|−}}
| {{sup|251}}Bk
| (3/2+)
{{Isotopes table/footer}}
Actinides vs fission products
{{Actinidesvsfissionproducts}}
{{clear}}
References
{{Reflist}}
- Isotope masses from:
- {{NUBASE 2003}}
- Half-life, spin, and isomer data selected from the following sources.
- {{NUBASE 2003}}
- {{NNDC}}
- {{CRC85|chapter=11}}
{{Navbox element isotopes}}