Step-by-step explanation:
Barium is an alkaline earth metal and it's atomic number is 56 with electronic configuration [tex]1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{10}4s^{2}4p^{6}4d^{10}5s^{2}5p^{6}6s^{2}.
This results in more number of shells in a barium atom. Hence, valence shell moves far away from the nucleus due to this there is very less attraction between the valence electrons and nucleus of Ba atom.
Thus, we can conclude that elements like barium located toward the bottom of a group have a lower attraction for their valence electrons because they have greater atomic mass.