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 Manganese compounds where manganese is in oxidation state +7, which are mostly restricted to the unstable oxide MnO, compounds of the intensely purple permanganate anion MnO, and a few oxyhalides (MnOF and MnOCl), are powerful oxidizing agents. Compounds with oxidation states +5 (blue) and +6 (green) are strong oxidizing agents and are vulnerable to disproportionation. The most stable oxidation state for manganese is +2, which has a pale pink color, and many manganese(II) compounds are known, such as manganese(II) sulfate (MnSO) and manganese(II) chloride (MnCl). This oxidation state is also seen in the mineral rhodochrosite (manganese(II) carbonate). Manganese(II) most commonly