# How do alpha and beta particles ionise surrounding particles?

I've been wondering about this question for a while. If you have alpha and beta particles released from a radioactive core, how do they ionise surrounding particles?

Alpha particles are the nuclei of He, i.e. lacking the two electrons they carry a charge of $+2e$, while beta particles are either electrons or positrons and thus carrying a charge of $\mp 1e$. Positrons meeting other atoms' electrons annihilate thus leaving a positive ionization. The other particles may just carry enough momentum to transfer the energy required for the ionization of shell electrons.