The mass defect is therefore also known as the binding energy of the nucleus. It measures the difference between the stability of the products of the reaction and the starting materials.
The larger the binding energy, the more stable the nucleus.
The mass defect of an atom reflects the stability of the nucleus.
It is equal to the energy released when the nucleus is formed from its protons and neutrons.
Electron capture leads to a decrease of one in the charge on the nucleus.