Curium (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 Cm in 1944, which has 146 neutrons.
There are 19 known ranging from Cm to Cm. There are also ten known . The longest-lived isotope is 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.
List of isotopes
|-id=Curium-233
| rowspan=2|Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 137
| rowspan=2|233.05077(9)
| rowspan=2|
|
beta decay (80%)
| Am
| rowspan=2|3/2+#
|-
|
alpha decay (20%)
| Pu
|-id=Curium-234
| rowspan=3|Cm
| rowspan=3 style="text-align:right" | 96
| rowspan=3 style="text-align:right" | 138
| rowspan=3|234.050159(18)
| rowspan=3|
| β (71%)
| Am
| rowspan=3|0+
|-
| α (27%)
| Pu
|-
| SF (2%)
| (various)
|-id=Curium-235
| rowspan=2|Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 139
| rowspan=2|235.05155(11)#
| rowspan=2|
| β? (96%)
| Am
| rowspan=2|5/2+#
|-
| α (4%)
| Pu
|-id=Curium-236
| rowspan=2|Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 140
| rowspan=2|236.051372(19)
| rowspan=2|
| β (82%)
| Am
| rowspan=2|0+
|-
| α (18%)
| Pu
|-id=Curium-237
| Cm
| style="text-align:right" | 96
| style="text-align:right" | 141
| 237.05287(8)
| >10# min
| α (?%)
| Pu
| 5/2+#
|-id=Curium-238
| rowspan=3|Cm
| rowspan=3 style="text-align:right" | 96
| rowspan=3 style="text-align:right" | 142
| rowspan=3|238.053082(13)
| rowspan=3|
|
Electron capture? (96.11%)
| Am
| rowspan=3|0+
|-
| α (3.84%)
| Pu
|-
| SF (0.048%)
| (various)
|-id=Curium-239
| rowspan=2|Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 143
| rowspan=2|239.05491(16)
| rowspan=2|
| β
| Am
| rowspan=2|7/2−#
|-
| α (6.2x10%)
| Pu
|-id=Curium-240
| rowspan=2|Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 144
| rowspan=2|240.0555282(20)
| rowspan=2|
| α
| Pu
| rowspan=2|0+
|-
| SF (3.9×10%)
| (various)
|-id=Curium-241
| rowspan=2|Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 145
| rowspan=2|241.0576512(17)
| rowspan=2|
| EC (99.0%)
| Am
| rowspan=2|1/2+
|-
| α (1.0%)
| Pu
|-id=Curium-242
| rowspan=3|Cm
| rowspan=3 style="text-align:right" | 96
| rowspan=3 style="text-align:right" | 146
| rowspan=3|242.0588342(12)
| rowspan=3|
| α
| Pu
| rowspan=3|0+
|-
| SF (6.2×10%)
| (various)
|-
|
Cluster decay (1.1×10%)
[Heaviest known nuclide to undergo cluster decay]
|
PbSi
|-id=Curium-242m
| rowspan=2 style="text-indent:1em" | Cm
| rowspan=2 colspan="3" style="text-indent:2em" | 2800(100) keV
| rowspan=2 |
| SF?
| (various)
| rowspan=2 |
|-
| IT?
| Cm
|-id=Curium-243
| rowspan=3|Cm
| rowspan=3 style="text-align:right" | 96
| rowspan=3 style="text-align:right" | 147
| rowspan=3|243.0613873(16)
| rowspan=3|
| α (99.71%)
| Pu
| rowspan=3|5/2+
|-
| EC (0.29%)
| Am
|-
| SF (5.3×10%)
| (various)
|-id=Curium-243m
| style="text-indent:1em" | Cm
| colspan="3" style="text-indent:2em" | 87.4(1) keV
|
| IT
| Cm
| 1/2+
|-id=Curium-244
| rowspan=2|Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 148
| rowspan=2|244.0627506(12)
| rowspan=2|
| α
| Pu
| rowspan=2|0+
|-
| SF (1.37×10%)
| (various)
|-id=Curium-244m1
| style="text-indent:1em" | Cm
| colspan="3" style="text-indent:2em" | 1040.181(11) keV
|
| IT
| Cm
| 6+
|-id=Curium-244m2
| style="text-indent:1em" | Cm
| colspan="3" style="text-indent:2em" | 1100(900)# keV
| >500 ns
| SF
| (various)
|
|-id=Curium-245
| rowspan=2|Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 149
| rowspan=2|245.0654910(12)
| rowspan=2|
| α
| Pu
| rowspan=2|7/2+
|-
| SF (6.1×10%)
| (various)
|-id=Curium-245m
| style="text-indent:1em" | Cm
| colspan="3" style="text-indent:2em" | 355.92(10) keV
|
| IT
| Cm
| 1/2+
|-id=Curium-246
| rowspan=2|Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 150
| rowspan=2|246.0672220(16)
| rowspan=2|
| α (99.97%)
| Pu
| rowspan=2|0+
|-
| SF (0.02615%)
| (various)
|-id=Curium-246m
| style="text-indent:1em" | Cm
| colspan="3" style="text-indent:2em" | 1179.66(13) keV
|
| IT
| Cm
| 8−
|-id=Curium-247
| Cm
| style="text-align:right" | 96
| style="text-align:right" | 151
| 247.070353(4)
|
| α
| Pu
| 9/2−
|-id=Curium-247m1
| style="text-indent:1em" | Cm
| colspan="3" style="text-indent:2em" | 227.38(19) keV
|
| IT
| Cm
| 5/2+
|-id=Curium-247m2
| style="text-indent:1em" | Cm
| colspan="3" style="text-indent:2em" | 404.90(3) keV
|
| IT
| Cm
| 1/2+
|-id=Curium-248
| rowspan=2|Cm
| rowspan=2 style="text-align:right" | 96
| rowspan=2 style="text-align:right" | 152
| rowspan=2|248.0723491(25)
| rowspan=2|
| α (91.61%)
| Pu
| rowspan=2|0+
|-
| SF (8.39%)
| (various)
|-id=Curium-248m
| style="text-indent:1em" | Cm
| colspan="3" style="text-indent:2em" | 1458.1(10) keV
|
| IT
| Cm
| 8−#
|-id=Curium-249
| Cm
| style="text-align:right" | 96
| style="text-align:right" | 153
| 249.0759540(25)
|
| β
| Bk
| 1/2+
|-id=Curium-249m
| style="text-indent:1em" | Cm
| colspan="3" style="text-indent:2em" | 48.76(4) keV
|
|
|
| 7/2+
|-id=Curium-250
| rowspan=3|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
[The nuclide with the lowest atomic number known (almost surely) to undergo spontaneous fission as the main decay mode]
| (various)
| rowspan=3|0+
|-
| α (?%)
| Pu
|-
| β (?%)
| Bk
|-id=Curium-251
| Cm
| style="text-align:right" | 96
| style="text-align:right" | 155
| 251.082285(24)
|
| β
| Bk
| (3/2+)
Actinides vs fission products
-
Isotope masses from:
-
Half-life, spin, and isomer data selected from the following sources.
