Let's look at them in more detail. Ionising alpha Alpha particles are made from the nuclei of helium. The atomic number of helium is 2 so an alpha particle carries a double positive charge . This means that they tend to collide with plenty of other atoms. Therefore, they cause a lot of ionisation by pulling electrons off the atoms.
Beta radiation is a stream of fast moving electrons.
They tend to pass through the air and solid matter without many collisions with other atoms. So beta radiation is only weakly ionising. However, it means that it has a long range in air and will pass through paper, aluminium and steel . However, it is stopped by lead or thick pieces of other metals. Penetrating gamma Gamma radiation is at the high frequency end of the electromagnetic spectrum .