When a nucleus in an atom undergoes a radioactive decay, the atomic...

In $\alpha$ decay, the atomic number decreases by $2$ and the mass number decreases by $4$.

In $\beta$ decay, the atomic number changes by $1$ (increases in $\beta^{-}$ and decreases in $\beta^{+}$) while the mass number remains unchanged.

In $\gamma$ decay, neither the atomic number nor the mass number changes, as it only involves a transition between nuclear energy levels.

Thus, the atomic number and/or mass number change for $\alpha$ and $\beta$ radiations but not for $\gamma$ radiation.

Answer: change for $\alpha$ and $\beta$ radiations but not for $\gamma$ radiation.