What best defines a beta particle?

What best defines a beta particle?

• A. A helium nucleus emitted in alpha decay.
• B. A gamma photon emitted during decay.
• C. A high-speed electron emitted in the decay of a radioactive isotope.
• D. A proton released during beta decay.

Answer: (C)

Beta decay changes the type of nucleon inside the nucleus while releasing a fast charged particle. In the common form, a neutron becomes a proton and an electron is emitted along with an antineutrino. That fast electron is the beta particle. The mass number stays the same, but the atomic number increases by one. This distinguishes beta emission from alpha decay, which ejects a helium nucleus, and from gamma emission, which is just a high-energy photon leaving the atom without changing its nuclear composition. Protons aren’t emitted in beta decay (that would be a different pathway, beta-plus decay would involve a positron). The key idea is that a beta particle is the electron (or positron) produced during beta decay.

Beta decay changes the type of nucleon inside the nucleus while releasing a fast charged particle. In the common form, a neutron becomes a proton and an electron is emitted along with an antineutrino. That fast electron is the beta particle. The mass number stays the same, but the atomic number increases by one. This distinguishes beta emission from alpha decay, which ejects a helium nucleus, and from gamma emission, which is just a high-energy photon leaving the atom without changing its nuclear composition. Protons aren’t emitted in beta decay (that would be a different pathway, beta-plus decay would involve a positron). The key idea is that a beta particle is the electron (or positron) produced during beta decay.