# Why is the binding energy per nucleon not zero for hydrogen atom?

The lone proton has not to be worked on against any electrostatic force. So where does the energy come from? What is mass defect for a hydrogen nucleus?

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If you are talking about the "average" naturally occurring hydrogen atom then you have a weighted average that includes the occasional deuteron with it's 2.2 MeV binding energy (i.e. 1.1 MeV per nucleon). – dmckee Nov 7 '12 at 13:51
I think this question would be much better if there was a clearly identified reference. Doing a Google image search, it looks like most graphs define a proton to be the baseline. I don't doubt you could find one that shows what the question asks, it might be relative to the average binding energy or something else. – AlanSE Nov 7 '12 at 14:05
@dmckee : yes, perhaps you are right. perhaps i am talking about the average.it is right if i think that the binding energy per nucleon of hydrogen atom, 1H1 only, is zero, right? – Swapnanil Saha Nov 11 '12 at 14:55
but it is zero,per nucleon, at least in the binding energy tables :upload.wikimedia.org/wikipedia/commons/5/53/… – anna v Nov 12 '12 at 10:06