Isotope "nuclide", and is still sometimes used in contexts where "nuclide" might be more appropriate, such as nuclear technology and nuclear medicine. An isotope and/or nuclide is specified by the name of the particular element (this indicates the atomic number) followed by a hyphen and the mass number (e.g. helium-3, helium-4, carbon-12, carbon-14, uranium-235 and uranium-239). When a chemical symbol is used, e.g. "C" for carbon, standard notation (now known as "AZE notation" because "A" is the mass number, "Z" the atomic number, and E for element) is to indicate the mass number (number of nucleons) with a superscript at the
Isotopes of curium Isotopes of curium Curium (Cm) 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 Cm in 1944, which has 146 neutrons. There are 21 known radioisotopes with atomic masses ranging from Cm to Cm. There are also four known nuclear isomers (Cm, Cm, Cm, and Cm). The longest-lived isotope is Cm, 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