What is the Q Value of Beta Minus Decay?

[harsh22902]

TL;DR

The given image shows the derivation of Q value in a beta minus decay. Now according to my understanding the electron released is formed from a neutron which converts to a proton and an electron within the nucleus , and has no relation with the orbital electrons. Then why is it that in the second bracket it has been given (Z+1)*m(e) and not Z*m(e) only.

 

[vanhees71]

It's because they define and calculate it in terms of the mass of the neutral atoms, which includes the mass of the electrons, and the daughter of a $\beta$-decay nucleus has one more proton and thus also the corresponding atom one more electron than the mother nucleus/atom.

 

[harsh22902]

That clears it for me , thank you !