Question

Describe two reasons why an alpha particle is less penetrating than a beta or gamma particle.

Answer 1

I'm not at home, so I can't open my chem book for specific values but I can give you the basic idea.

Alpha rays are just helium nuclei, whereas beta rays are electrons and gamma rays are photons having high energy.

Alpha particles also have bigger wavelengths than beta and gamma particles too. Bigger wavelength means less penetration through our skin.

Answer 2

So alpha particles (helium nucleus) are much bigger in mass than beta particles (which are electrons) and gamma particles (which are photons, light particles). Look at the picture I attached that shows how far through lead each particle travels.

Answer 3

In summary, 1) alpha particles are more massive, 2) and they contain less energy than beta and gamma particles. You can add that they have bigger wavelength but that is the same as saying less energy.