During radioactivity, unstable atoms try to gain stability by emitting alpha particles, beta particles or gamma particles. Beta particles, also known as beta rays, are a high speed, high energy electron (β-) or positron(β+) emitted from the radioactive decay of the atomic nucleus. This process is called beta decay. An unstable atomic nucleus with an excess of neutrons will emit electrons (β-) during the β decay. If the unstable atomic nucleus has an excess of the proton, then a positron(β+) is emitted during β decay.

10 Important Properties of Beta Particles

Property 1: Beta particles (β – particles) are fast-moving electrons or positrons with high energy emitted by the radioactive decay of an atomic nucleus.

Property 2: Penetrating power of beta particles is higher than α-particles. They can penetrate through a thin metal foil. 

Property 3: The ionising power of β-particles is 100 times lesser than α-particles. Higher ionisation means a higher damage to the living tissue.

Property 4: Both the electric field and magnetic field affect the β-particles. Applying Fleming’s left-hand rule, it is observed that the direction of deflection of β-particles is opposite to that of α-particles.

Property 5: Their speed can go up to 9/10 times the speed of light.

Property 6: In a β – decay the atomic number of the daughter nucleus increases by one but the mass number remains the same.

Property 7: Beta particles have negligible mass. They are much lighter than alpha particles.

Property 8: β – particles can be stopped by a thin layer of aluminium or plastic.

Property 9: They affect the photographic plate.

Property 10: They lose energy fast when they interact with matter and take a haphazard path as they move through air or other materials.