like chromium, manganese can use all its valence electrons in its compounds, exhibiting every possible positive oxidation state, with the +2, +4, and +7 states most common (table 23.5).As the oxidation state of manganese rises, its valence state electronegativity increasae and its oxides change from basic to acidic. manganese oxide (MnO) is basic, and manganese oxide (Mn2O3) is amphoteric. Manganese(IV) oxide (MnO2) is insoluble and shows no acid-base proprtties. (It is used in dry-cell and alkaline batteries as the oxidizing agent in a redox reaction with zinc (Gallery, Section 21.5) Manganese(VII) oxide