Question

Define 'Mass defect' and 'Binding energy' of a nucleus. Describe the 'Fission process' on the basis of binding energy per nucleon.

Hint:

In nuclear fission, the binding energy per nucleon increases for lighter nuclei, which is why energy is released during fission of heavy nuclei.

Answer 1

Mass Defect: The mass defect of a nucleus is the discrepancy between the sum of the masses of its constituent protons and neutrons and the nucleus's actual measured mass. This lost mass is converted into binding energy, which stabilizes the nucleus.

Binding Energy: Binding energy is the energy needed to break apart a nucleus into its individual protons and neutrons. It directly corresponds to the energy equivalent of the mass defect.

Fission Process: Nuclear fission occurs when a heavy nucleus divides into two lighter nuclei, releasing energy in the process. This energy release happens because the binding energy per nucleon in the resulting smaller nuclei is higher than in the original nucleus. The energy liberated during fission stems from this difference in binding energy per nucleon before and after the division.

Consequently, during fission, the cumulative binding energy of the resulting fragments exceeds the binding energy of the parent nucleus, with the excess energy being released.