Question

How do the mass number and atomic change as a particle goes through alpha decay?

Answer 1

Since an alpha particles is a helium nucleus, it involves the loss of 2 protons and 2 neutrons. As a result, the atom the loses an alpha particle decreases its mass number by four ( 2 protons and 2 neutrons) and decreases it's atomic number by 2 ( it loses two protons).