# What is the equation for sodium 22 undergoing electron capture?

Jan 14, 2015

Sodium-22 undergoes electron capture according to the following nuclear equation:

$\text{_-1^0"e" + _11^22"Na" -> _10^22"Ne}$

Notice that the electron capture of Na-22 results in nuclear transmutation; the inner-orbital electron is captured by the nucleus, the result being the formation of a neutron from the combination of said electron with a proton from the nucleus.

This process will reduce the atomic number by 1 ($11 \to 10$), but leave the atomic mass unchanged.

You will sometimes see the electron capture of Na-22 being described as a positron emission. The nuclear equation for that process is

$\text{_11^22"Na" -> _10^22"Ne} + {\beta}^{+} + {\nu}_{e}$, where

${\beta}^{+}$ - a positron - the antiparticle of the electron (same mass, opposite charge);
${\nu}_{e}$ - a neutrino;

Electron capture can be viewed as the equivalent process to positron decay, since both processes result in the same nuclear transmutation - the formation of $\text{_10^22"Ne}$.