Nuclear Chemistry: Explaining Binding Energy and Mass Defect

[spizma]

I'm doing a nuclear chemistry project right now, and I am able to solve all of the problems involving binding energy and mass defect, however I have one conceptual question. Why is it that when the nucleons combine with each other they let off energy? At first I thought it was their kinetic energy being let off because they're being held in place by the strong nuclear force, but that seems wrong for some reason. My book doesn't go into any detail about this, can someone try explaining it? Thanks in advance.

 

[humanino]

Hi,

it is not kinetic energy, it is potential energy. The same holds for any kind of bound system, nuclear, electromagnetic, gravitational.

Take the Moon-Earth system for instance. In principle, the mass of the bound system has less mass than the sum of the masses of the Earth and the Moon measured independantly of each other when far away apart in empty vacuum. Of course, one cannot actually perform such an experiment. But the mass defect merely comes from E=mc2 and the potential energy.

 

[spizma]

In the case of subatomic particles, what kind of potential energy is it?

 

[malawi_glenn]

For nucleons : The Strong Nuclear force (Residual color force)

For quarks: The Color force and EM force.

etc.