Question

What is the equation for sodium 22 undergoing electron capture?

Answer 1

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

`""_-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->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

`""_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 `""_10^22"Ne"`.