Isotopes of curium

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Isotopes of curium  (96Cm)
Main isotopes [1] Decay
abun­dance half-life (t1/2) mode pro­duct
242Cm synth 162.8 d α 238Pu
SF –
34Si 208Pb
243Cmsynth29.1 yα 239Pu
ε 243Am
SF–
244Cmsynth18.11 yα 240Pu
SF–
245Cmsynth8250 yα 241Pu
SF–
246Cmsynth4760 yα 242Pu
SF–
247Cmsynth1.56×107 yα 243Pu
248Cmsynth3.480×105 yα 244Pu
SF–
250Cmsynth8300 ySF–
α 246Pu
β− 250Bk

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.

Contents

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 isomer is 246mCm with a half-life of 1.12 seconds.

List of isotopes

Nuclide
[n 1] 		Z N Isotopic mass (Da)
[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]
233Cm96137233.05077(8)23+13
−6 s		 β+ (80%)233Am3/2+#
α (20%)229Pu
234Cm96138234.05016(2)52(9) sβ+ (71%)234Am0+
α (27%)230Pu
SF (2%)(various)
235Cm [4] 96139235.05143(22)#300+250
−100 s		β+ (99.0%)235Am(5/2+)
α (1.0%)231Pu
236Cm96140236.05141(22)#6.8(8) minβ+ (82%)236Am0+
α (18%)232Pu
SF (<0.1%) [5] (various)
237Cm [6] [4] 96141237.05290(22)#>660 sβ+237Am(5/2+)
α (<1%)233Pu
238Cm [6] 96142238.05303(4)2.2(4) h EC (~94%)238Am0+
α (~6%)234Pu
239Cm [1] 96143239.05496(11)#2.5(4) hβ+239Am(7/2−)
α (6.2x10−3%)235Pu
240Cm96144240.0555295(25)27(1) dα (99.5%)236Pu0+
EC (.5%)240Am
SF (3.9×10−6%)(various)
241Cm96145241.0576530(23)32.8(2) dEC (99%)241Am1/2+
α (1%)237Pu
242Cm [n 7] 96146242.0588358(20)162.8(2) dα238Pu0+
SF (6.33×10−6%)(various)
CD (10−14%) [n 8] 208Pb
34Si
242mCm2800(100) keV180(70) ns
243Cm96147243.0613891(22)29.1(1) yα (99.71%)239Pu5/2+
EC (.29%)243Am
SF (5.3×10−9%)(various)
243mCm87.4(1) keV1.08(3) μsIT243Cm1/2+
244Cm [n 7] 96148244.0627526(20)18.10(2) yα240Pu0+
SF (1.34×10−4%)(various)
244m1Cm1040.188(12) keV34(2) ms IT 244Cm6+
244m2Cm1100(900)# keV>500 nsSF(various)
245Cm96149245.0654912(22)8.5(1)×103 yα241Pu7/2+
SF (6.1×10−7%)(various)
245mCm355.92(10) keV290(20) nsIT245Cm1/2+
246Cm96150246.0672237(22)4.76(4)×103 yα (99.97%)242Pu0+
SF (.0261%)(various)
246mCm1179.66(13) keV1.12(0.24) sIT246Cm8-
247Cm96151247.070354(5)1.56(5)×107 yα243Pu9/2−
247m1Cm227.38(19) keV26.3(0.3) μsIT247Cm5/2+
247m2Cm404.90(3) keV100.6(0.6) nsIT247Cm1/2+
248Cm96152248.072349(5)3.48(6)×105 yα (91.74%)244Pu0+
SF (8.26%)(various)
248mCm1458.1(1) keV146(18) μsIT248Cm(8-)
249Cm96153249.075953(5)64.15(3) minβ−249Bk1/2(+)
249mCm48.758(17) keV23 μsα245Pu(7/2+)
250Cm96154250.078357(12)8300# ySF (74%) [n 9] (various)0+
α (18%)246Pu
β− (8%)250Bk
251Cm96155251.082285(24)16.8(2) minβ−251Bk(1/2+)
This table header & footer:
  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. 1 2 3 # – 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. 1 2 Most common isotopes
  8. ↑ Heaviest known nuclide to undergo cluster decay
  9. ↑ The nuclide with the lowest atomic number known to undergo spontaneous fission as the main decay mode

Actinides vs fission products

Actinides and fission products by half-life
Actinides [7] by decay chain Half-life
range (a)		 Fission products of 235U by yield [8]
4n 4n + 1 4n + 2 4n + 3 4.5–7%0.04–1.25%<0.001%
228 Ra№ 4–6 a 155 Euþ
244 Cmƒ 241 Puƒ 250 Cf 227 Ac№ 10–29 a 90 Sr 85 Kr 113m Cdþ
232 Uƒ 238 Puƒ 243 Cmƒ 29–97 a 137 Cs 151 Smþ 121m Sn
248 Bk [9] 249 Cfƒ 242m Amƒ141–351 a

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

241 Amƒ 251 Cfƒ [10] 430–900 a
226 Ra№ 247 Bk1.3–1.6 ka
240 Pu 229 Th 246 Cmƒ 243 Amƒ4.7–7.4 ka
245 Cmƒ 250 Cm8.3–8.5 ka
239 Puƒ24.1 ka
230 Th№ 231 Pa№32–76 ka
236 Npƒ 233 Uƒ 234 U№ 150–250 ka 99 Tc₡ 126 Sn
248 Cm 242 Pu 327–375 ka 79 Se₡
1.53 Ma 93 Zr
237 Npƒ 2.1–6.5 Ma 135 Cs₡ 107 Pd
236 U 247 Cmƒ 15–24 Ma 129 I₡
244 Pu80 Ma

... nor beyond 15.7 Ma [11]

232 Th№ 238 U№ 235 Uƒ№0.7–14.1 Ga

Related Research Articles

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Radium (88Ra) has no stable or nearly stable isotopes, and thus a standard atomic weight cannot be given. The longest lived, and most common, isotope of radium is 226Ra with a half-life of 1600 years. 226Ra occurs in the decay chain of 238U. Radium has 34 known isotopes from 201Ra to 234Ra.

There are 39 known isotopes of radon (86Rn), from 193Rn to 231Rn; all are radioactive. The most stable isotope is 222Rn with a half-life of 3.823 days, which decays into 218
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Bismuth (83Bi) has 41 known isotopes, ranging from 184Bi to 224Bi. Bismuth has no stable isotopes, but does have one very long-lived isotope; thus, the standard atomic weight can be given as 208.98040(1). Although bismuth-209 is now known to be radioactive, it has classically been considered to be a stable isotope because it has a half-life of approximately 2.01×1019 years, which is more than a billion times the age of the universe. Besides 209Bi, the most stable bismuth radioisotopes are 210mBi with a half-life of 3.04 million years, 208Bi with a half-life of 368,000 years and 207Bi, with a half-life of 32.9 years, none of which occurs in nature. All other isotopes have half-lives under 1 year, most under a day. Of naturally occurring radioisotopes, the most stable is radiogenic 210Bi with a half-life of 5.012 days. 210mBi is unusual for being a nuclear isomer with a half-life multiple orders of magnitude longer than that of the ground state.

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Naturally occurring gadolinium (64Gd) is composed of 6 stable isotopes, 154Gd, 155Gd, 156Gd, 157Gd, 158Gd and 160Gd, and 1 radioisotope, 152Gd, with 158Gd being the most abundant (24.84% natural abundance). The predicted double beta decay of 160Gd has never been observed; only a lower limit on its half-life of more than 1.3×1021 years has been set experimentally.

Promethium (61Pm) is an artificial element, except in trace quantities as a product of spontaneous fission of 238U and 235U and alpha decay of 151Eu, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. It was first synthesized in 1945.

There are 39 known isotopes and 17 nuclear isomers of tellurium (52Te), with atomic masses that range from 104 to 142. These are listed in the table below.

Antimony (51Sb) occurs in two stable isotopes, 121Sb and 123Sb. There are 35 artificial radioactive isotopes, the longest-lived of which are 125Sb, with a half-life of 2.75856 years; 124Sb, with a half-life of 60.2 days; and 126Sb, with a half-life of 12.35 days. All other isotopes have half-lives less than 4 days, most less than an hour.

Naturally occurring ruthenium (44Ru) is composed of seven stable isotopes. Additionally, 27 radioactive isotopes have been discovered. Of these radioisotopes, the most stable are 106Ru, with a half-life of 373.59 days; 103Ru, with a half-life of 39.26 days and 97Ru, with a half-life of 2.9 days.

Natural yttrium (39Y) is composed of a single isotope yttrium-89. The most stable radioisotopes are 88Y, which has a half-life of 106.6 days and 91Y with a half-life of 58.51 days. All the other isotopes have half-lives of less than a day, except 87Y, which has a half-life of 79.8 hours, and 90Y, with 64 hours. The dominant decay mode below the stable 89Y is electron capture and the dominant mode after it is beta emission. Thirty-five unstable isotopes have been characterized.

Arsenic (33As) has 33 known isotopes and at least 10 isomers. Only one of these isotopes, 75As, is stable; as such, it is considered a monoisotopic element. The longest-lived radioisotope is 73As with a half-life of 80 days. Arsenic has been proposed as a "salting" material for nuclear weapons. A jacket of 75As, irradiated by the intense high-energy neutron flux from an exploding thermonuclear weapon, would transmute into the radioactive isotope 76As with a half-life of 1.0778 days and produce approximately 1.13 MeV gamma radiation, significantly increasing the radioactivity of the weapon's fallout for several hours. Such a weapon is not known to have ever been built, tested, or used.

Germanium (32Ge) has five naturally occurring isotopes, 70Ge, 72Ge, 73Ge, 74Ge, and 76Ge. Of these, 76Ge is very slightly radioactive, decaying by double beta decay with a half-life of 1.78 × 1021 years (130 billion times the age of the universe).

Berkelium (97Bk) is an artificial element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 243Bk in 1949. There are 20 known radioisotopes, from 230Bk and 233Bk to 253Bk, and 6 nuclear isomers. The longest-lived isotope is 247Bk with a half-life of 1,380 years.

Fermium (100Fm) is a synthetic element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be discovered was 255Fm in 1952. 250Fm was independently synthesized shortly after the discovery of 255Fm. There are 20 known radioisotopes ranging in atomic mass from 241Fm to 260Fm, and 4 nuclear isomers, 247mFm, 250mFm, 251mFm, and 253mFm. The longest-lived isotope is 257Fm with a half-life of 100.5 days, and the longest-lived isomer is 247mFm with a half-life of 5.1 seconds.

Californium (98Cf) is an artificial element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 245Cf in 1950. There are 20 known radioisotopes ranging from 237Cf to 256Cf and one nuclear isomer, 249mCf. The longest-lived isotope is 251Cf with a half-life of 898 years.

Einsteinium (99Es) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be discovered was 253Es in 1952. There are 18 known radioisotopes from 240Es to 257Es, and 3 nuclear isomers. The longest-lived isotope is 252Es with a half-life of 471.7 days, or around 1.293 years.

Mendelevium (101Md) is a synthetic element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 256Md in 1955. There are 17 known radioisotopes, ranging in atomic mass from 244Md to 260Md, and 5 isomers. The longest-lived isotope is 258Md with a half-life of 51.3 days, and the longest-lived isomer is 258mMd with a half-life of 57 minutes.

Dubnium (105Db) is a synthetic element, thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 261Db in 1968. The 13 known radioisotopes are from 255Db to 270Db, and 1–3 isomers. The longest-lived known isotope is 268Db with a half-life of 16 hours.

References

  1. 1 2 Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  2. ↑ Côté, Benoit; Eichler, Marius; Yagüe López, Andrés; Vassh, Nicole; Mumpower, Matthew R.; Világos, Blanka; Soós, Benjámin; Arcones, Almudena; Sprouse, Trevor M.; Surman, Rebecca; Pignatari, Marco; Pető, Mária K.; Wehmeyer, Benjamin; Rauscher, Thomas; Lugaro, Maria (26 February 2021). "129 I and 247 Cm in meteorites constrain the last astrophysical source of solar r-process elements". Science. 371 (6532): 945–948. arXiv: 2006.04833 . Bibcode:2021Sci...371..945C. doi:10.1126/science.aba1111. PMID   33632846. S2CID   232050526.
  3. ↑ 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.
  4. 1 2 Khuyagbaatar, J.; Heßberger, F. P.; Hofmann, S.; Ackermann, D.; Burkhard, H. G.; Heinz, S.; Kindler, B.; Kojouharov, I.; Lommel, B.; Mann, R.; Maurer, J.; Nishio, K. (12 October 2020). "α decay of Fm 243 143 and Fm 245 145 , and of their daughter nuclei". Physical Review C. 102 (4): 044312. doi:10.1103/PhysRevC.102.044312. ISSN   2469-9985. S2CID   241259726 . Retrieved 24 June 2023.
  5. ↑ Khuyagbaatar, J.; Heßberger, F. P.; Hofmann, S.; Ackermann, D.; Comas, V. S.; Heinz, S.; Heredia, J. A.; Kindler, B.; Kojouharov, I.; Lommel, B.; Mann, R.; Nishio, K.; Yakushev, A. (1 October 2010). "The new isotope 236Cm and new data on 233Cm and 237, 238, 240Cf" (PDF). The European Physical Journal A. 46 (1): 59–67. Bibcode:2010EPJA...46...59K. doi:10.1140/epja/i2010-11026-9. ISSN   1434-601X. S2CID   122809010 . Retrieved 24 June 2023.
  6. 1 2 Asai, M.; Tsukada, K.; Ichikawa, S.; Sakama, M.; Haba, H.; Nishinaka, I.; Nagame, Y.; Goto, S.; Kojima, Y.; Oura, Y.; Shibata, M. (20 June 2006). "α decay of 238Cm and the new isotope 237Cm". Physical Review C. 73 (6): 067301. doi:10.1103/PhysRevC.73.067301 . Retrieved 24 June 2023.
  7. ↑ 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.
  8. ↑ Specifically from thermal neutron fission of uranium-235, e.g. in a typical nuclear reactor.
  9. ↑ 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. Bibcode:1965NucPh..71..299M. doi:10.1016/0029-5582(65)90719-4.
    "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 [years]. No growth of Cf248 was detected, and a lower limit for the β− half-life can be set at about 104 [years]. No alpha activity attributable to the new isomer has been detected; the alpha half-life is probably greater than 300 [years]."
  10. ↑ This is the heaviest nuclide with a half-life of at least four years before the "sea of instability".
  11. ↑ 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.
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