Isotope electrons in the neutral (non-ionized) atom. Each atomic number identifies a specific element, but not the isotope; an atom of a given element may have a wide range in its number of neutrons. The number of nucleons (both protons and neutrons) in the nucleus is the atom's mass number, and each isotope of a given element has a different mass number. For example, carbon-12, carbon-13 and carbon-14 are three isotopes of the element carbon with mass numbers 12, 13 and 14 respectively. The atomic number of carbon is 6, which means that every carbon atom has 6 protons, so that
Isotopes of curium in the periodic table. The shortest-lived isomer is Cm with a half-life of 34 milliseconds. 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