In a typical helium atom, the nucleus has two protons and two neutrons. However, the mass of a helium atom is less than the combined mass of two protons and two neutrons. The explanation of this mass defect is found in Einstein's mass-energy equivalence
The energy required to cause these four nucleons to form a helium nucleus is created by a corresponding loss of mass. The nucleons of iron are bound with the highest energy, showing that iron is the most stable element.
Example:
Given the following information, find the binding energy of the isotope:
Z =1.00728amu, =1.00867amu, =15.9994amu.
If no mass were converted to energy, the 16O isotope would have a mass of
