How to Calculate Q Value for Beta-Decay Using Atomic Masses?

[PonderingMick]

Can someone please tell me how to calculate this?

My notes are such a mess. Is it as simple as Q = (Mx-My)c2 using atomic masses?

Cheers,

Mick

 

[Bob S]

I believe you have to also include the electron mass when you calculate the Q value for beta decay, because the electron (or positron) has to be created (in nearly every case):

Q = (M₁ - M₂)c² - m_ec²

There is a special case, called electron capture, or k-capture, where the nucleus captures an atomic electron and emits only a neutrino.

You can compare your numbers with this online Q-value calculator:

http://t2.lanl.gov/data/astro/molnix96/qbeta.html