Which statement accurately describes alpha particles?

Which statement accurately describes alpha particles?

• A. They are positively charged, relatively slow and weakly penetrating.
• B. They are fast and highly penetrating.
• C. They are negatively charged and undetectable.
• D. They are photons.

Answer: (A)

Alpha particles are helium nuclei, consisting of two protons and two neutrons, emitted from heavy atomic nuclei. They carry a +2 charge and have relatively large mass, so they move more slowly compared to other radiation and lose energy rapidly as they travel through matter. This combination makes them strongly ionizing—able to knock many electrons from atoms in a short path—yet they have limited range and are easily stopped by a sheet of paper or a few centimeters of air. They are not fast or highly penetrating like some other forms of radiation, and they are not negatively charged nor photons.

Alpha particles are helium nuclei, consisting of two protons and two neutrons, emitted from heavy atomic nuclei. They carry a +2 charge and have relatively large mass, so they move more slowly compared to other radiation and lose energy rapidly as they travel through matter. This combination makes them strongly ionizing—able to knock many electrons from atoms in a short path—yet they have limited range and are easily stopped by a sheet of paper or a few centimeters of air. They are not fast or highly penetrating like some other forms of radiation, and they are not negatively charged nor photons.