Manganese easy to oxidize. Manganese metal and its common ions are paramagnetic. Manganese tarnishes slowly in air and oxidizes ("rusts") like iron in water containing dissolved oxygen. Naturally occurring manganese is composed of one stable isotope, Mn. Eighteen radioisotopes have been isolated and described, ranging in atomic weight from 46 u (Mn) to 65 u (Mn). The most stable are Mn with a half-life of 3.7 million years, Mn with a half-life of 312.3 days, and Mn with a half-life of 5.591 days. All of the remaining radioactive isotopes have half-lives of less than three hours, and the majority of less
Manganese dioxide At temperatures of 400 °C, the salt decomposes, releasing and leaving a residue of purified manganese dioxide. These two steps can be summarized as: In another process manganese dioxide is carbothermically reduced to manganese(II) oxide which is dissolved in sulfuric acid. The filtered solution is treated with ammonium carbonate to precipitate . The carbonate is calcined in air to give a mixture of manganese(II) and manganese(IV) oxides. To complete the process, a suspension of this material in sulfuric acid is treated with sodium chlorate. Chloric acid, which forms in situ, converts any Mn(III) and Mn(II) oxides to the dioxide, releasing