Question

What is the difference between positron emission and electron emission?

Answer 1

Positron emission gives a new nucleus with the same mass number but an atomic number that is one less than the old one. Electron emission gives an atomic number that is one greater.

Both positrons and electrons are β particles. A positron is the antimatter counterpart of an electron (β⁻). A positron is a positive electron (β⁺).

Beta (β) emission is a process in which a nucleus emits a β particle (an electron or a positron). This allows the atom to get the optimal ratio of protons and neutrons.

β Emission

There are two types of β emission.

The emission of an electron is β⁻ decay. The nuclear symbol for a β⁻ particle is `""_-1^0"e"`.

The emission of a positron is β⁺ decay. The symbol for a β⁺ particle is `""_1^0"e"`.

β⁻ (Electron) Decay

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

`""_6^14"C" → _7^14"N" + _-1^0"e"`

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

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

`""_12^23"Mg" → _11^23"Na" + _1^0"e"`

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.