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When $\beta^-$ disintegration happens to a Carbon 14 atom, a neutron "turns into" a proton, and an electron is emitted. Therefore the result of the disintegration is a Nitrogen atom plus an electron (also an electron antineutrino, but that's not relevant here). My question is : is the nitrogen atom ionized ? Since it has $7$ protons, it needs $7$ electrons to be electrically neutral, but it only has the $6$ ones that the Carbon atom had, so it should have a supplement positive charge, shouldn't it ? Or does the emitted electron stay with the nitrogen atom so that it's neutral ?

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The ionisation energy of a nitrogen atom is about 14.5eV but in $^{14}$C beta decay the electron is emitted with an energy of 156keV, which is far higher than the ionisation energy. So beta decay will normally produce an N$^+$ ion and a free electron.

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  • $\begingroup$ Even if the original carbon atom was rather positive (e.g. CCl4, chloroform) the excess energy is still enough to escape not just the atom but the whole molecule. $\endgroup$ – MSalters Apr 8 '15 at 12:44
  • $\begingroup$ Thanks ! The book I have is a high school book and isn't very precise ; feel free to suggest me some further reading. $\endgroup$ – Asinus Apr 8 '15 at 14:43

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