Nuclear binding energy may be calculated from the difference in mass of a nucleus and the sum of the masses of the nucleus’s unbound neutrons and protons.
Once the mass difference, also known as the mass defect or mass deficit, is determined, Einstein’s mass-energy equivalence formula may be used to calculate the binding energy of any nucleus.
Calculating this once referred to as a “packing fraction” calculation by early nuclear scientists.
Final answer:
The mass defect per nucleon is called Nuclear binding energy