Does an atom gain or lose an electron during beta decay?
Quick Answer: It can do either.
There are two kinds of β particles, electrons and positrons.
An electron is a β⁻ particle. The antimatter counterpart of an electron is a positron or β⁺ particle.
When people speak of β decay, they usually mean β⁻ decay.
β⁻ decay is a process in which a nucleus emits an electron.
The nuclear symbol for a β⁻ particle is
Carbon-14 decays to nitrogen-14 by β⁻ emission.
The sum of the subscripts and the sum of the superscripts must be equal on each side of the equation. Thus, 6 = 7 – 1, and 14 = 14 + 0.
β⁺ (Positron) Decay
The emission of a positron is β⁺ decay.
The symbol for a β⁺ particle is
Magnesium-23 decays into sodium-23 by positron (β⁺) emission:
As before, the sum of the subscripts and the sum of the superscripts must be equal on each side of the equation. Thus, 12 = 11 + 1, and 23 = 23 + 0.
In β⁺ emission, the product has the same mass number and an atomic number that has decreased by 1.
The nucleus chooses the type of β decay that that gives it the most stable neutron-to-proton ratio.