Isotopes of curium
Artificial nuclides with atomic number of 96 but with different mass numbers From Wikipedia, the free encyclopedia
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.
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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.[2][3] The longest-lived known isomer is 246mCm with a half-life of 1.12 seconds.
List of isotopes
Summarize
Perspective
Nuclide [n 1] |
Z | N | Isotopic mass (Da)[4] [n 2][n 3] |
Half-life[1] [n 4] |
Decay mode[1] [n 5] |
Daughter isotope |
Spin and parity[1] [n 6][n 4] | ||||||||||||
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Excitation energy[n 4] | |||||||||||||||||||
233Cm | 96 | 137 | 233.050771(87) | 27(10) s | β+ (80%) | 233Am | 3/2+# | ||||||||||||
α (20%) | 229Pu | ||||||||||||||||||
234Cm | 96 | 138 | 234.050159(18) | 52(9) s | β+ (71%) | 234Am | 0+ | ||||||||||||
α (27%) | 230Pu | ||||||||||||||||||
SF (2%) | (various) | ||||||||||||||||||
235Cm | 96 | 139 | 235.05155(11)# | 7(3) min | β+ (96%) | 235Am | 5/2+# | ||||||||||||
α (4%) | 231Pu | ||||||||||||||||||
236Cm | 96 | 140 | 236.051372(19) | 6.8(8) min | β+ (82%) | 236Am | 0+ | ||||||||||||
α (18%) | 232Pu | ||||||||||||||||||
237Cm | 96 | 141 | 237.052869(80) | >10# min | α (?%) | 233Pu | 5/2+# | ||||||||||||
238Cm | 96 | 142 | 238.053082(13) | 2.2(4) h | EC (96.11%) | 238Am | 0+ | ||||||||||||
α (3.84%) | 234Pu | ||||||||||||||||||
SF (0.048%) | (various) | ||||||||||||||||||
239Cm | 96 | 143 | 239.05491(16) | 2.5(4) h | β+ | 239Am | 7/2−# | ||||||||||||
α (6.2x10−3%) | 235Pu | ||||||||||||||||||
240Cm | 96 | 144 | 240.0555282(20) | 30.4(37) d | α | 236Pu | 0+ | ||||||||||||
SF (3.9×10−6%) | (various) | ||||||||||||||||||
241Cm | 96 | 145 | 241.0576512(17) | 32.8(2) d | EC (99.0%) | 241Am | 1/2+ | ||||||||||||
α (1.0%) | 237Pu | ||||||||||||||||||
242Cm | 96 | 146 | 242.0588342(12) | 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 | 180(70) ns | |||||||||||||||||
243Cm | 96 | 147 | 243.0613873(16) | 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 | 1.08(3) μs | IT | 243Cm | 1/2+ | ||||||||||||||
244Cm | 96 | 148 | 244.0627506(12) | 18.11(3) y | α | 240Pu | 0+ | ||||||||||||
SF (1.37×10−4%) | (various) | ||||||||||||||||||
244m1Cm | 1040.181(11) keV | 34(2) ms | IT | 244Cm | 6+ | ||||||||||||||
244m2Cm | 1100(900)# keV | >500 ns | SF | (various) | |||||||||||||||
245Cm | 96 | 149 | 245.0654910(12) | 8250(70) y | α | 241Pu | 7/2+ | ||||||||||||
SF (6.1×10−7%) | (various) | ||||||||||||||||||
245mCm | 355.92(10) keV | 290(20) ns | IT | 245Cm | 1/2+ | ||||||||||||||
246Cm | 96 | 150 | 246.0672220(16) | 4706(40) y | α (99.97%) | 242Pu | 0+ | ||||||||||||
SF (0.02615%) | (various | ||||||||||||||||||
246mCm | 1179.66(13) keV | 1.12(24) s | IT | 246Cm | 8− | ||||||||||||||
247Cm | 96 | 151 | 247.0703527(41) | 1.56(5)×107 y | α | 243Pu | 9/2− | ||||||||||||
247m1Cm | 227.38(19) keV | 26.3(3) μs | IT | 247Cm | 5/2+ | ||||||||||||||
247m2Cm | 404.90(3) keV | 100.6(6) ns | IT | 247Cm | 1/2+ | ||||||||||||||
248Cm | 96 | 152 | 248.0723491(25) | 3.48(6)×105 y | α (91.61%)[n 9] | 244Pu | 0+ | ||||||||||||
SF (8.39%) | (various) | ||||||||||||||||||
248mCm | 1458.1(10) keV | 146(18) μs | IT | 248Cm | 8−# | ||||||||||||||
249Cm | 96 | 153 | 249.0759540(25) | 64.15(3) min | β− | 249Bk | 1/2+ | ||||||||||||
249mCm | 48.76(4) keV | 23 μs | α | 245Pu | 7/2+ | ||||||||||||||
250Cm | 96 | 154 | 250.078358(11) | 8300# y | SF (74%)[n 10] | (various) | 0+ | ||||||||||||
α (?%) | 246Pu | ||||||||||||||||||
β− (?%) | 250Bk | ||||||||||||||||||
251Cm | 96 | 155 | 251.082285(24) | 16.8(2) min | β− | 251Bk | (3/2+) | ||||||||||||
This table header & footer: |
- mCm – 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).
- # – 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 CD: Cluster decay SF: Spontaneous fission - ( ) spin value – Indicates spin with weak assignment arguments.
- Theoretically capable of β+β+ decay to 242Pu
- Heaviest known nuclide to undergo cluster decay
- Theoretically capable of β−β− decay to 248Cf
- The nuclide with the lowest atomic number known to undergo spontaneous fission as the main decay mode
Actinides vs fission products
Summarize
Perspective
Actinides[5] by decay chain | Half-life range (a) |
Fission products of 235U by yield[6] | ||||||
---|---|---|---|---|---|---|---|---|
4n | 4n + 1 | 4n + 2 | 4n + 3 | 4.5–7% | 0.04–1.25% | <0.001% | ||
228Ra№ | 4–6 a | 155Euþ | ||||||
248Bk[7] | > 9 a | |||||||
244Cmƒ | 241Puƒ | 250Cf | 227Ac№ | 10–29 a | 90Sr | 85Kr | 113mCdþ | |
232Uƒ | 238Puƒ | 243Cmƒ | 29–97 a | 137Cs | 151Smþ | 121mSn | ||
249Cfƒ | 242mAmƒ | 141–351 a |
No fission products have a half-life | |||||
241Amƒ | 251Cfƒ[8] | 430–900 a | ||||||
226Ra№ | 247Bk | 1.3–1.6 ka | ||||||
240Pu | 229Th | 246Cmƒ | 243Amƒ | 4.7–7.4 ka | ||||
245Cmƒ | 250Cm | 8.3–8.5 ka | ||||||
239Puƒ | 24.1 ka | |||||||
230Th№ | 231Pa№ | 32–76 ka | ||||||
236Npƒ | 233Uƒ | 234U№ | 150–250 ka | 99Tc₡ | 126Sn | |||
248Cm | 242Pu | 327–375 ka | 79Se₡ | |||||
1.33 Ma | 135Cs₡ | |||||||
237Npƒ | 1.61–6.5 Ma | 93Zr | 107Pd | |||||
236U | 247Cmƒ | 15–24 Ma | 129I₡ | |||||
244Pu | 80 Ma |
... nor beyond 15.7 Ma[9] | ||||||
232Th№ | 238U№ | 235Uƒ№ | 0.7–14.1 Ga | |||||
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References
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