Well I've just started on kinetics and there are a few things I am absolutely confused about!

  1. First of all, is a neutron actually made up of a proton and electron? If yes, then how is this possible?
  2. In K-electron capture where the electron of the K-Shell is captured by the nucleus, doesn't the species become positively charged or ionized as it is losing an electron?
  3. When metastable technetium disintegrates into normal technetium and a gamma particle, what is the change brought about? Isn't the technetium on both sides of the equation basically the same?

3 Answers 3

  1. No, as hey answered, neutrons are made of two down quarks and an up quark. Protons are made of two up quarks and a down quark. It is the conversion of a down quark into an up quark that results in the neutron --> proton conversion. Read here for more information about this reaction.

    The confusion with this probably comes from the fact that net reaction in a neutron to proton conversion is $n^{0} \rightarrow p^{+} + e^{-} + \overline{\nu_e}$, so it looks like a neutron is falling apart into three sub-particles.

  2. No, the atom will not become ionized from this event itself. Consider what is happening in this reaction: $p^{+} + e^{-} \rightarrow n^{0} + \nu_e$

    Yes, an electron is removed from the atom, but at the same time a proton is as well. We should know that the atoms remains neutral because of conservation of charge. If the atom has no net charge at the beginning of the reaction, and no charged particles are ejected, it must be neutral at the end of the reaction as well.

  3. Jon Custer's response is spot on here. Gamma ray emission represents the movement of the nucleus from a metastable state to its ground state via the release of electromagnetic radiation.


For 3., this is nuclear physics (or chemistry - Glenn Seaborg was a chemist). You clearly understand electron structure of an atom - there are various energy levels that can be occupied, and the ground state has all the electrons at the lowest states. An excited (neutral) atom has an electron occupying a higher electron state, and it can decay back to the ground state by emitting a photon. Well, the nucleus has various energy states for the protons and neutrons to occupy (the forces and math aren't the same, but the general idea is similar). A metastable nuclear configuration is not in the ground state. However, it can drop into the ground state, and has to release the energy somehow, and just like the electron it does so by emitting a photon, just a high energy one. Gammas are from nuclear transitions, x-rays from electronic transitions.


Is neutron actually made up of a proton and electron?

Answer is no. Neutron is neutral(no charge) doesn't mean it is made up Electron and Proton. The neutron is made of two Down and one Up quark.


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