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Isotopes of curium
Encyclopedia
Curium
(Cm) is an artificial element, and thus a standard atomic mass
cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope
synthesized was 242Cm in 1944.
There are 21 known radioisotopes with atomic mass
es ranging from 232Cm to 252Cm. There are also four known nuclear isomer
s (243mCm, 244mCm, 245mCm, and 249mCm). The longest-lived isotope is 247Cm, with a half-life
of 15.6 million years. The longest-lived isomer is 244mCm with a half-life of 34 milliseconds.
Curium
Curium is a synthetic chemical element with the symbol Cm and atomic number 96. This radioactive transuranic element of the actinide series was named after Marie Skłodowska-Curie and her husband Pierre Curie. Curium was first intentionally produced and identified in summer 1944 by the group of...
(Cm) is an artificial element, and thus a standard atomic mass
Atomic mass
The atomic mass is the mass of a specific isotope, most often expressed in unified atomic mass units. The atomic mass is the total mass of protons, neutrons and electrons in a single atom....
cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
synthesized was 242Cm in 1944.
There are 21 known radioisotopes with atomic mass
Atomic mass
The atomic mass is the mass of a specific isotope, most often expressed in unified atomic mass units. The atomic mass is the total mass of protons, neutrons and electrons in a single atom....
es ranging from 232Cm to 252Cm. There are also four known nuclear isomer
Nuclear isomer
A nuclear isomer is a metastable state of an atomic nucleus caused by the excitation of one or more of its nucleons . "Metastable" refers to the fact that these excited states have half-lives more than 100 to 1000 times the half-lives of the other possible excited nuclear states...
s (243mCm, 244mCm, 245mCm, and 249mCm). The longest-lived isotope is 247Cm, with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 15.6 million years. The longest-lived isomer is 244mCm with a half-life of 34 milliseconds.
Table
nuclide symbol |
Z (p Proton The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number.... ) |
N (n Neutron The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of... ) |
isotopic mass (u) |
half-life Half-life Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to... |
decay mode(s)Abbreviations: CD: Cluster decay Cluster decay Cluster decay is a type of nuclear decay in which a parent atomic nucleus with A nucleons and Z protons emits a cluster of Ne neutrons and Ze protons heavier than an alpha particle but lighter than a typical binary fission fragment Cluster decay (also named heavy particle radioactivity or heavy... EC: Electron capture Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... IT: Isomeric transition Isomeric transition An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer.... SF: Spontaneous fission Spontaneous fission Spontaneous fission is a form of radioactive decay characteristic of very heavy isotopes. Because the nuclear binding energy reaches a maximum at a nuclear mass greater than about 60 atomic mass units , spontaneous breakdown into smaller nuclei and single particles becomes possible at heavier masses... |
daughter isotopesBold for stable isotopes |
spin |
---|---|---|---|---|---|---|---|
excitation energy | |||||||
232Cm | 96 | 136 | 1? min | 0+ | |||
233Cm | 96 | 137 | 233.05077(8) | 1# min | β+ Beta decay In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a... |
233Am | 3/2+# |
α Alpha decay Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle and thereby transforms into an atom with a mass number 4 less and atomic number 2 less... |
229Pu | ||||||
234Cm | 96 | 138 | 234.05016(2) | 51(12) s | β+ | 234Am | 0+ |
α | 230Pu | ||||||
235Cm | 96 | 139 | 235.05143(22)# | 5# min | β+ | 235Am | 5/2+# |
α | 231Pu | ||||||
236Cm | 96 | 140 | 236.05141(22)# | 10# min | β+ | 236Am | 0+ |
α | 232Pu | ||||||
237Cm | 96 | 141 | 237.05290(22)# | 20# min | β+ | 237Am | 5/2+# |
α | 233Pu | ||||||
238Cm | 96 | 142 | 238.05303(4) | 2.4(1) h | EC Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... (90%) |
238Am | 0+ |
α (10%) | 234Pu | ||||||
239Cm | 96 | 143 | 239.05496(11)# | ~2.9 h | β+ (99.9%) | 239Am | (7/2-) |
α (.1%) | 235Pu | ||||||
240Cm | 96 | 144 | 240.0555295(25) | 27(1) d | α (99.5%) | 236Pu | 0+ |
EC (.5%) | 240Am | ||||||
SF Spontaneous fission Spontaneous fission is a form of radioactive decay characteristic of very heavy isotopes. Because the nuclear binding energy reaches a maximum at a nuclear mass greater than about 60 atomic mass units , spontaneous breakdown into smaller nuclei and single particles becomes possible at heavier masses... (3.9×10−6%) |
(various) | ||||||
241Cm | 96 | 145 | 241.0576530(23) | 32.8(2) d | EC (99%) | 241Am | 1/2+ |
α (1%) | 237Pu | ||||||
242CmMost common isotopes | 96 | 146 | 242.0588358(20) | 162.8(2) d | α | 238Pu | 0+ |
SF (6.33×10−6%) | (various) | ||||||
CD Cluster decay Cluster decay is a type of nuclear decay in which a parent atomic nucleus with A nucleons and Z protons emits a cluster of Ne neutrons and Ze protons heavier than an alpha particle but lighter than a typical binary fission fragment Cluster decay (also named heavy particle radioactivity or heavy... (10−14%)Heaviest known nuclide to undergo cluster decay Cluster decay Cluster decay is a type of nuclear decay in which a parent atomic nucleus with A nucleons and Z protons emits a cluster of Ne neutrons and Ze protons heavier than an alpha particle but lighter than a typical binary fission fragment Cluster decay (also named heavy particle radioactivity or heavy... |
208Pb 34Si |
||||||
β+β+ (rare) | 242Pu | ||||||
243Cm | 96 | 147 | 243.0613891(22) | 29.1(1) a | α (99.71%) | 239Pu | 5/2+ |
EC (.29%) | 243Am | ||||||
SF (5.3×10−9%) | (various) | ||||||
243mCm | 87.4(1) keV | 1.08(3) µs | 1/2+ | ||||
244Cm | 96 | 148 | 244.0627526(20) | 18.10(2) a | α | 240Pu | 0+ |
SF (1.34×10−4%) | (various) | ||||||
244mCm | 1040.188(12) keV | 34(2) ms | IT Isomeric transition An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer.... |
244Cm | 6+ | ||
245Cm | 96 | 149 | 245.0654912(22) | 8.5(1)×103 a | α | 241Pu | 7/2+ |
SF (6.1×10−7%) | (various) | ||||||
245mCm | 355.90(10) keV | 290(20) ns | 1/2+ | ||||
246Cm | 96 | 150 | 246.0672237(22) | 4.76(4)×103 a | α (99.97%) | 242Pu | 0+ |
SF (.0261%) | (various) | ||||||
247Cm | 96 | 151 | 247.070354(5) | 1.56(5)×107 a | α | 243Pu | 9/2- |
248Cm | 96 | 152 | 248.072349(5) | 3.48(6)×105 a | α (91.74%) | 244Pu | 0+ |
SF (8.26%) | (various) | ||||||
β-β- (rare) | 248Cf | ||||||
249Cm | 96 | 153 | 249.075953(5) | 64.15(3) min | β- | 249Bk | 1/2(+) |
249mCm | 48.758(17) keV | 23 µs | (7/2+) | ||||
250Cm | 96 | 154 | 250.078357(12) | 8,300# a | SF (80%)Lightest nuclide to undergo spontaneous fission Spontaneous fission Spontaneous fission is a form of radioactive decay characteristic of very heavy isotopes. Because the nuclear binding energy reaches a maximum at a nuclear mass greater than about 60 atomic mass units , spontaneous breakdown into smaller nuclei and single particles becomes possible at heavier masses... as the main decay mode |
(various) | 0+ |
α (11%) | 246Pu | ||||||
β- (9%) | 250Bk | ||||||
251Cm | 96 | 155 | 251.082285(24) | 16.8(2) min | β- | 251Bk | (1/2+) |
252Cm | 96 | 156 | 252.08487(32)# | <1 d | β- | 252Bk | 0+ |