Manganese

Manganese is a chemical element with the symbol Mn and atomic number 25. It is not found as a free element in nature;[not verified in body] it is often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy uses, particularly in stainless steels.

First isolated in 1774, manganese is mainly used in the production of steel. It is familiar in the laboratory in the form of the deep violet salt potassium permanganate. It occurs at the active sites in some enzymes.[3] Of particular interest is the use of a Mn-O cluster, the oxygen-evolving complex, in the production of oxygen by plants.

Manganese is a silvery-gray metal that resembles iron. It is hard and very brittle, difficult to fuse, but easy to oxidize.[4] Manganese metal and its common ions are paramagnetic.[5] Manganese tarnishes slowly in air and oxidizes (“rusts”) like iron in water containing dissolved oxygen.

Naturally occurring manganese is composed of one stable isotope, 55Mn. Several radioisotopes have been isolated and described, ranging in atomic weight from 44 u (44Mn) to 69 u (69Mn). The most stable are 53Mn with a half-life of 3.7 million years, 54Mn with a half-life of 312.2 days, and 52Mn 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 than one minute.

The primary decay mode in isotopes lighter than the most abundant stable isotope, 55Mn, is electron capture and the primary mode in heavier isotopes is beta decay.[6] Manganese also has three meta states.[6]