manganese chromate is an oxide with the chemical symbol MnO2, and atomic number 25. It is the third most abundant transition metal in the Earth’s crust. In period four and group seven of the periodic table, it is positioned between chromium (Cr) and iron (Fe).
It occurs mainly as brownstone and is mined for its mineral form of ferromanganese in the steel industry. In addition, it is added to aluminum alloys to improve their tensile strength and corrosion resistance. It is also used in a wide variety of chemicals to remove oxygen and sulfur from ores and is a cathode for alkaline manganese batteries.
The chemical structure of manganese can be defined with the aid of different oxidation states. The oxidation state +2 is the most stable. However, it can occur in other oxidation states as a two-valent manganese and as a three-valent manganese in minerals like brownstone or rhodochrosite.
In biology, manganese is an essential element for all living organisms and it is a component of many enzymes. It plays a role in photosynthesis, in the formation of enzyme structures and in redox reactions. In some bacteria it is also involved in energy production.
For example, in the bacterium Shewanella putrefaciens, manganese is used to perform anaerobic respiration by using Mn4 + as the terminal electron acceptor and reducing it to Mn2 +. It is also involved in redox reactions by dismutating superoxide radicals.
It is important to control the amount of manganese deposited in drinking water and food sources. Exposure to excessive amounts of manganese can lead to permanent neurological disorders such as facial muscle spasms, hallucination and violent behavior. In addition, it can cause Parkinson’s disease and dementia.