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Proton and neutron

  1. Sep 4, 2004 #1
    isn't a neutron more massive thatn a proton?
  2. jcsd
  3. Sep 4, 2004 #2
    It is. Free neutrons are even unstable and decay with a lifetime of something like 12min. To my big surprise, when I looked it up, the mass-difference was much more than I expected: 2.5 times the mass of an electron (I expected not much more than the electron mass).
  4. Sep 5, 2004 #3
    The neutron is about 0.2% more massive than a proton, which translates to an energy difference of 1.29 MeV. I believe that the added mass of the electron plus the proton equals very close to the mass of the neutron.
  5. Sep 5, 2004 #4
    This is impossible, the mass of the proton is 1.67262158 × 10-27 kilograms, while the mass of the electron is 9.10938188 × 10-31 kilograms. This means that the proton has a mass more than 10^4 times that of the electron.
  6. Sep 5, 2004 #5
    How come when a proton turns into a neutron (as in nuclear fusion in the Sun) it gives out energy AND gains in mass, where does all the extra energy come from
  7. Sep 5, 2004 #6
    Masses given for particles are the masses of free particles. When particles bond together the created particle can have a lower mass than the sum of the constituents (to some extend one can even see this as the reason why stable bound states exist). The mass-difference is called the bonding energy.

    @ArmoSkater: You seem to have mistaken my 1st post.
  8. Sep 5, 2004 #7
  9. Sep 5, 2004 #8
    I think he means that he thought the difference in mass between a neutron and a proton would be close to the mass of an electron.
  10. Sep 10, 2004 #9
    What, the *** are you guys talking about ???

  11. Sep 10, 2004 #10
    They are trying to make us swallow that a neutron = a proton + an electron :tongue2:
  12. Sep 10, 2004 #11
    Based upon what evidence ???

    What is the underlying theory here ...

  13. Sep 10, 2004 #12
    That would simply be wrong.
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