A Level Physics Practice Exam

Alpha radiation consists of which particles?

1. Electrons

2. Protons

3. Neutrons

4. Two protons and two neutrons

The correct answer is: Two protons and two neutrons

Alpha radiation consists of helium nuclei, which are made up of two protons and two neutrons. This specific configuration of particles is what characterizes alpha particles. The presence of two protons gives the alpha particle a positive charge, while the two neutrons contribute to its mass but do not affect its charge. In terms of nuclear reactions, alpha radiation is a common form of decay for heavy radioactive isotopes, where they emit an alpha particle to become more stable. Because alpha particles have a relatively large mass compared to other forms of radiation, such as beta particles (electrons) or gamma rays (photons), they have a different range and capability of penetration into materials. Understanding that an alpha particle is essentially a helium nucleus helps clarify why it is distinctly different from other particle types found in radiation, such as electrons or neutrons, which do not constitute an alpha particle.