Radioactive penetration
Alpha particles are stopped by a hand, beta by thin aluminium and gamma rays by concrete
Alpha particles
Alpha particles come from the nucleus of a radioactive atom. They consist of 2 protons and 2 neutrons; hence have a 2+ charge. A few centimeters of air will stop them.
Alpha radiation consists of helium nuclei, \(_2^4He_{}^{2 + }\)
Beta particles
A beta particle is an electron, \(_{ - 1}^{\,\,\,0}e_{}^ -\).
Since the nucleus does not contain electrons, it is thought that a beta particle is formed when a neutron splits up into a proton and an electron.
While it will pass through air, it cannot penetrate thin metal foil.
Gamma waves
Gamma waves come from the nucleus of a radioactive atom. They are electronegative waves.
They do not change the nature of an atom.
Thick lead or concrete will absorb gamma rays.