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Isotopes of curium


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

... nor beyond 15.7 M years

Legend for superscript symbols
₡  has thermal neutron capture cross section in the range of 8–50 barns
ƒ  fissile
metastable isomer
№  naturally occurring radioactive material (NORM)
þ  neutron poison (thermal neutron capture cross section greater than 3k barns)
†  range 4–97 y: Medium-lived fission product
‡  over 200,000 y: Long-lived fission product

Curium (Cm) is an artificial element with an atomic number of 96. Because it is an artificial element, a standard atomic mass cannot be given, and it has no stable isotopes. The first isotope synthesized was 242Cm in 1944, which has 146 neutrons. All of the isotopes are radioactive.

There are 21 known radioisotopes with atomic masses ranging from 232Cm to 252Cm. There are also four known nuclear isomers (243mCm, 244mCm, 245mCm, and 249mCm). The longest-lived isotope is 247Cm, with a half-life of 15.6 million years – several orders of magnitude longer than the half-life of all known nuclei of elements beyond curium in the periodic table. The shortest-lived isomer is 244mCm with a half-life of 34 milliseconds.



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