Isotopes of curium

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.