The elements of the periodic table are arranged in columns called groups, and rows called periods. Elements in the same group have the same outer electronic configuration as its group number (Elements of Group 2 have two electrons in its valence shell). Thus, the chemical properties of elements belonging to the same group are very similar. For instance, all elements of group II form Cations with a +2 charge. There are trends in reactivity observed moving down the group. Elements of Group 2 become more reactive as we move down the group due to following reasons: Distance of valence electrons from the nucleus increases. Increased number of intervalence shells, result in increased shielding effect on valence electrons. These two factors outweigh the effect of increased nuclear force. Hence, it becomes easier to remove electrons, moving down the group. 