Why acidic character of oxides of group 15 elements decreases down the group?
Group 15 elements are Nitrogen (N) (7), Phosphorus (P) (15), Arsenic (As) (33), Antimony (Sb) (51), Bismuth (Bi) (83).
Acidic character of oxides of group 15 elements decreases and basicity increases down the group. As we move down the group, the atomic size increases, electronegativity decreases and metallic character increases. All these elements form two types of oxides: E2O3 and E2O5. The oxide in the higher oxidation state of the element is more acidic than that of lower oxidation state. Oxides of Nitrogen and phosphorous are acidic. As and Sb are amphoteric and Bismuth are basic.