What are alpha-particles? - Leaving Cert Physics - Question 1 - 2016

Alpha-particles are essentially helium nuclei, represented by the symbol (^4_2He). They consist of two protons and two neutrons.

As a form of nuclear radiation, alpha-particles are emitted during certain types of radioactive decay processes. Their relatively large mass compared to other forms of radiation makes them less penetrative; for instance, they can be stopped by a sheet of paper or even human skin.

In summary, alpha-particles can be classified as a type of (nuclear) radiation, specifically characterized by their composition of helium nuclei.