Here's why:

* Beta particles are electrons or positrons. Electrons have a charge of -1, and positrons have a charge of +1.

* The term "beta particle" refers to a type of radiation. It's not a specific particle with a fixed charge like a proton or neutron.

Therefore, beta particles can have a charge of -1 (for electrons) or +1 (for positrons). They never have a charge of 2.