Unpacking Nuclear Fission: Understanding Binding Energy

[Kaushik96]

During nuclear fission a heavy nucleus of low binding energy splits into two middle mass nuclei with high binding energy ! From where does this energy suddenly come from ??

And why is the binding energy of heavy nuclei lesser than that of middle mass nuclei ??

 

[mfb]

During nuclear fission a heavy nucleus of low binding energy splits into two middle mass nuclei with high binding energy ! From where does this energy suddenly come from ??

Binding energy in nuclei is always negative. A high binding energy corresponds to a low-energy state.

And why is the binding energy of heavy nuclei lesser than that of middle mass nuclei ??

Electromagnetic repulsion of the protons (positive contribution to binding energy) grows quicker than the negative contribution from the strong interaction.

 

[VantagePoint72]

Binding energy in nuclei is always negative.

No, the potential energy in nuclei, with the zero defined at infinite nucleon separation, is always negative. Being defined as the energy you have to supply to break up an atom, binding energy in nuclei is always positive.

 

[mfb]

Ok, you are right, I used the wrong word.

 

[Kaushik96]

Binding energy in nuclei is always negative. A high binding energy corresponds to a low-energy state.

I was not able to understand the first part ! Could you explain in detail ??

 

[mfb]

Binding energy in nuclei is always positive = potential energy of a nucleus is always negative.
If you combine x protons and y neutrons to a (possible) nucleus, energy is released - otherwise, the nucleus would not be a bound state at all.