Converting Helium back to Hydrogen?

[The Mak]

I am trying to find the reason why a helium atom cannot be turned back into a hydrogen atom.

We know in a star that through nucleosynthesis helium is formed from hydrogen and the process continues to form heavier elements. Is there a similar, but in reverse process where lighter elements are formed from heavier elements?

 

[DaveC426913]

Yes. It's called fission.

But it takes a lot of energy to separate helium into hydrogen.

 

[The Mak]

Thanks for the quick reply.

 

[Studiot]

You need to study the binding energy curve.

Basically atoms lighter than iron release energy in fusion and take in energy for fission

whilst

Basically atoms heavier than iron release energy in fission and take in energy for fusion

Here is a more complete answer

http://csep10.phys.utk.edu/astr162/lect/energy/bindingE.html

also look up the packing fraction curve.