Beta particles

Definition

Beta particles are high-energy, high-speed electrons or positrons emitted from a radioactive nucleus during beta decay. They have a charge of either -1 (electron) or +1 (positron) and can penetrate materials more effectively than alpha particles.

5 Must Know Facts For Your Next Test

1. Beta decay occurs when a neutron in an unstable nucleus is converted into a proton, emitting a beta particle and an antineutrino.
2. There are two types of beta decay: beta-minus (β⁻) decay, which emits an electron, and beta-plus (β⁺) decay, which emits a positron.
3. Beta particles have greater penetrating power than alpha particles but less than gamma rays. They can pass through paper but are generally stopped by plastic or thin metal sheets.
4. The energy spectrum of beta particles is continuous because the energy is shared between the emitted beta particle and an accompanying neutrino.
5. In nuclear equations, beta-minus decay increases the atomic number by one while keeping the mass number constant.

Review Questions

• What type of particle is emitted during beta-minus decay?
• How do the atomic number and mass number change during beta-plus decay?
• Why do beta particles have a continuous energy spectrum?

Related terms

Alpha Particles: Alpha particles are helium nuclei consisting of two protons and two neutrons. They have low penetration power and can be stopped by paper or skin.

Gamma Rays: Gamma rays are high-energy electromagnetic waves emitted from a nucleus as it changes from an excited state to a ground energy state. They have high penetration power.

Neutron: A neutron is a subatomic particle found in the nucleus of an atom. It has no electric charge and plays a key role in stabilizing the nucleus.