The atomic mass of an element is the weighted average of the masses of its isotopes The mass defect of a nucleus is the difference between the total mass of a nucleus and the sum of the masses of all its constituent nucleons

The binding energy (BE) of a nucleus is equal to the amount of energy released in forming the nucleus, or the mass defect multiplied by the speed of light squared The atomic nucleus is composed of protons and neutrons

mass defect of a nucleus — the difference between the total mass of a nucleus and the sum of the masses of all its constituent nucleons. mass defect — difference between the mass of a nucleus and the total mass of its constituent nucleons. binding energy (BE) — energy needed to break a nucleus into its constituent protons and neutrons. isotopes — nuclei having the same number of protons but different numbers of neutrons.