Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

B Cu's 29th ionization energy

  1. Sep 6, 2017 #1
    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 !
     
  2. jcsd
  3. Sep 6, 2017 #2

    Charles Link

    User Avatar
    Homework Helper

    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! :) :)
     
    Last edited: Sep 6, 2017
  4. Sep 6, 2017 #3

    blue_leaf77

    User Avatar
    Science Advisor
    Homework Helper

    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.
     
  5. Sep 6, 2017 #4

    Charles Link

    User Avatar
    Homework Helper

    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. :)
     
  6. Sep 6, 2017 #5

    blue_leaf77

    User Avatar
    Science Advisor
    Homework Helper

    I see, but it's not like we can mine natural Cu 29th from nature like we do 235 U, despite the low abundance.
     
  7. Sep 6, 2017 #6

    Charles Link

    User Avatar
    Homework Helper

    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.
     
  8. Sep 8, 2017 #7
    I'm tryin to say that if we give that much energy to Cu by nuclear reaction then we could create that :)
     
  9. Sep 8, 2017 #8

    blue_leaf77

    User Avatar
    Science Advisor
    Homework Helper

    Theoretically that should be possible but I have no idea whether someone has tried this. Recently however, physicists have been able to create bare atoms using photoionization by free-electron laser such as this one. Also if my memory serves me right, the professor in the class I once took in my college spoke about creating bare atoms in a collider or so. Again, I am certain though if that was what he really said back then.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted