Nuclei – Notes

Atomic masses and composition of Nucleus
Atoms of the same element having different mass numbers are called isotopes.
The percentage of a particular isotope of an element found in the nature is known as its relative abundance.
The average mass of an atom or the atomic mass is obtained by the weighted average of the masses of its different isotopes.
Nucleus of an atom contains neutral or charge-less particles called neutrons apart from positively charged protons.
Atomic number, Z, of an element, indicates the number of protons in its nucleus.
Atomic mass number, A, of an element, indicates the total number of nucleons in its nucleus.
Neutron number, indicates the total number of neutrons in the nucleus. (N= A-Z)
Isobars are nuclides of different elements having the same atomic mass number, A.
Isotones are nuclides of different elements having same number of neutrons.

Nuclear Binding Energy and Nuclear Stability
Mass defect (Δm) is the difference between the theoretically expected mass of the nucleus and the actual mass of the nucleus.