Answer to Question #165944 in Physics for Sam

Question

Write out the nuclear decay equation for the beta -plus decay of aluminium -26 (Z=13) to an isotope of magnesium. (The chemical symbols of aluminium  and magnesium are Al and Mg respectively)

Answer 1

By definition, the beta -plus decay happens when the nucleus emmits a positron $e^+$ and a electron neutrino $\nu_e$ . Since positron is positively charged particle, according to the charge conservation, the charge of the remaining nucleus should be decreased by one. But since positron (as well as electron) does not influence on the mass number, the mass number remains the same. Thus, obtain:

$$^{26}_{13}Al \to\space ^{26}_{12}Mg + e^+ + \nu_e$$