# Does an atom gain or lose an electron during beta decay?

Aug 14, 2014

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.

β⁻ decay

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 $\text{_-1^0"e}$.

Carbon-14 decays to nitrogen-14 by β⁻ emission.

$\text{_6^14"C}$$\text{ _7^14"N}$ + ₋₁⁰e

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.

In β⁻ emission, the product has the same mass number and an atomic number that has increased by 1.

β⁺ (Positron) Decay

The emission of a positron is β⁺ decay.

The symbol for a β⁺ particle is $\text{_1^0"e}$.

Magnesium-23 decays into sodium-23 by positron (β⁺) emission:

$\text{_12^23"Mg" → _11^23"Na" + _1^0"e}$

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. 