# Cu's 29th ionization energy

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So I was playing with periodic table and discovered Cu's 29th ionization energy(cu with no electron) is 1116105 KJ/mole .

Then i searched on google to convert to MeV which is 6.9661798e+21 , then I thought that one uranium 235 produce 200mev
so to make that you would need around 3.5e+19 atoms(0.00005812022 mole) which means 0.01366080898g of it(practically more than it)

I'm just wowed !

## Answers and Replies

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So the 6.966 E+21 MeV is for one mole=6.02E+23 atoms. The Bohr atom formula has a ## Z^2 ## in the numerator, and with ## Z=1 ## for hydrogen, you get ## E=13.6 \, eV ##. That would make ## E=(29^2)(13.6)=11,440 \, eV ##, and for one mole it would be ## (N_A )(11,440)=(6.02 E+23)(11,440)=6.90 \,E+27 \, eV=6.90 \,E+21 \, MeV ##, so I agree with your calculation. ## \\ ## Welcome to Physics Forums! :) :)

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blue_leaf77
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then I thought that one uranium 235 produce 200mev
so to make that you would need around 3.5e+19 atoms(0.00005812022 mole) which means 0.01366080898g of it(practically more than it)
I am missing your point here, while your calculation is correct I cannot get your idea why you are comparing the process which consumes energy (to ionize Cu 29th) and the process which produce energy (from 235 U). Nevertheless, the reason there is such big difference is that in the second part you are considering nuclear reaction which only has respect on the nuclear structure and not on the electronic one as is considered in the ionization part. The nuclear energy levels have typical energy spacing in the order of MeV.
Btw it's 200 MeV not meV, I know it's typo but it may cause people not familiar with nuclear reaction to understand that the meV is correct.

Homework Helper
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I am missing your point here, while your calculation is correct I cannot get your idea why you are comparing the process which consumes energy (to ionize Cu 29th) and the process which produce energy (from 235 U). Nevertheless, the reason there is such big difference is that in the second part you are considering nuclear reaction which only has respect on the nuclear structure and not on the electronic one as is considered in the ionization part. The nuclear energy levels have typical energy spacing in the order of MeV.
Btw it's 200 MeV not meV, I know it's typo but it may cause people not familiar with nuclear reaction to understand that the meV is correct.
The electron capture of a ## Cu^{+29} ## ion would produce that much energy. For a first posting, I think the OP came up with something interesting. :)

blue_leaf77
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The electron capture of a Cu+29 Cu^{+29} ion would produce that much energy.
I see, but it's not like we can mine natural Cu 29th from nature like we do 235 U, despite the low abundance.

Homework Helper
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I see, but it's not like we can mine natural Cu 29th from nature like we do 235 U, despite the low abundance.
I think the OP is basically comparing the .0114 MeV per atom from this process, if we could get it to occur, with the 200 MeV for a Uranium atom. And yes, like you stated, the process consumes energy, so there is really no practical use for this=it's simply a calculation that can be done with the Bohr model of the atom for ## Z=29 ##. To produce a ## Cu^{+29} ## ion, the first 28 electrons would need to be removed, and then the 29th one would require this energy to remove it, which is readily calculated.

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I'm tryin to say that if we give that much energy to Cu by nuclear reaction then we could create that :)

blue_leaf77