In an alpha particle, consisting of two neutrons and two protons, is emitted from the nucleus of an atom. the daughter element will have an atomic number 2 less than and an atomic mass 4 less than the parent element.

In alpha decay, an alpha particle is emitted.

Explanation:

Alpha decay is defined as the decay process where an alpha particle is emitted. In this process, a heavier nuclei decays into a lighter nuclei. The alpha particle emitted carries a charge of +2 units and a mass of 4 units.

The emitted alpha particle is also known as helium nucleus.

In this decay process, the atomic number of the parent atom decreases by 2 units and the mass number decreases by 4 units.

The chemical equation for alpha decay process follows:

Hence, in alpha decay, an alpha particle is emitted.