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Beta Decay question

  1. Aug 2, 2011 #1
    Beta decay is when a neutron creates a proton and an electron and the electron is then expelled, right?

    So I was wondering, why would the new atom formed not be an ion?
    If the neutron became a proton, the mass number should stay the same, and the atomic number should increase by 1 since there is an extra proton now... but there is an extra proton without an extra electron, so shouldn't that make an ion?

    (since the charges don't add up)
     
  2. jcsd
  3. Aug 2, 2011 #2

    Drakkith

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    I would say yes. It would be an Ion until it captured an electron.
     
  4. Aug 2, 2011 #3
    The electron that's emitted quickly loses energy and is eventually recaptured. Also beta decay is when a proton emits a positron and turns into a neutron. The positron will eventually annihilate with an electron so charge balance is maintained.
     
  5. Aug 2, 2011 #4
    thanks.. I was just wondering because my study book didn't mention it turning into an ion, which was weird
     
  6. Aug 2, 2011 #5

    Drakkith

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    I don't believe this is correct. Per wikipedia:
    I think that the electron that is emitted CAN be captured, but I don't think it always occurs. It probably depends on the energy of the emitted electron.
     
  7. Aug 2, 2011 #6

    Drakkith

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    It probably was considered to be obvious or just overlooked.
     
  8. Aug 3, 2011 #7
    It is highly unlikely that the beta would be captured by the atom that emitted it since it would have to lose a great deal of energy very quickly. Even the weakest beta emitters such as tritium are over 1keV (18keV max for tritium), much more than the binding energy of the atomic orbitals. Since the energy spectrum of beta emitters is continuous rather than discrete (such as alpha emitters), there is a finite probability of a low enough energy that it could be captured, but I imagine it's so small as to be negligible.

    Also, to be more precise, a neutron doesn't "create" the proton/electron/electron antineutrino. The neutron decays into the particles.
     
  9. Aug 3, 2011 #8

    sophiecentaur

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    Charge has to be conserved but, in the short term, not necessarily where the even takes place - the electron that goes away leaves behind it a proton which is 'yearning' for a partner from somewhere. It's not fussy where it is to come from.
     
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