Manganese is an ancient metal and was discovered as a distinct element in 1774. It is used as pigment and for making various alloys with corrosion resistant properties.
History and Discovery
The use of manganese in the form of black colored pyrolusite (now identified as manganese dioxide) dates back to the 18th century in the region Magnesia, Greece. Various oxides of manganese have been used in ancient times as pigments due to their unique and brilliant colors. Manganese pigment has been found in cave paintings around 30,000 years ago . It was used by Romans and Egyptians to remove or add color to glass. Manganese was discovered in a relatively impure form by Gottlieb Gahn in 1774. Ever since its discovery as a distinct element, manganese has been used to make steel and as protective coating against corrosion and rust.
|Periodic Table Classification||Group 7
|State at 20C||Solid|
|Electron Configuration||[Ar] 3d5 4s2|
|Electron Shell||2, 8, 13, 2|
|Density||7.43 g.cm-3 at 20°C|
|Atomic Mass||54.94 g.mol -1|
|Electronegativity according to Pauling||1.55|
Manganese is an abundant element. It is found in about 1000 ppm in the Earth’s crust. And it is ranked the 12th most abundant element on Earth, with considerable amounts present in water and soil. Manganese does not exist in its free elemental form. It is present in mineral, mostly in combination with iron. The most common minerals of manganese include braunite, pyrolusite and psilomelane. Pyrolusite (MnO2) is the most important ore of manganese. The largest deposits of manganese are present in South Africa, which reached around 3.4 million tons in 2011 . Other countries that produce manganese include India, China, Brazil and Gabon. Manganese is present in herbs, tea and spinach, eggs, soybeans, rice, grains and green beans.
Manganese is a greyish-pink metal. It resembles iron in its physical appearance. It is brittle and hard. Manganese has a paramagnetic nature. when exposed to air and moisture, it undergoes slow oxidation that leads to rusting. Manganese is a dense metal, with a density of 7. 43 g.cm-3 at room temperature.
Manganese is a reactive metal in its pure elemental form. It reacts with water and is burned in the presence of oxygen. Manganese dissolves in dilute acids. In compounds, the common oxidation states of manganese are +2, +3, +4 and +6, while the most stable oxidation state is +2. These compounds include manganese chloride, manganese carbonate and manganese sulphate.
Significance and Uses
- Manganese is widely used in making various industrially important alloys such as stainless steel.
- Manganese in its ionic form is used as pigments in various industries. For instance, manganese oxide is used to make violet colored glass.
- Manganese is used in alkaline and zinc-carbon batteries as cathode.
- Manganese oxide is used in making fertilizers.
- Potassium permanganate is used as a common disinfectant.
Manganese is a neurotoxic element. It can lead to damage to neurons and nervous system if inhaled in large amount. It has been found to linked with Parkinson’s disease in miners working with manganese. Manganese contamination in water has been a source of various intellectual impairments in humans, especially children. In trace amounts, however, manganese is an essential micronutrient. As in biological system, manganese is used as an essential cofactor for various enzymes. It is part of the photosynthetic complex in plants and carry out vital superoxide detoxification reactions in humans . Manganese is present in around 12mg in human body, most of which is present in the bones. Manganese deficiency can lead to various health problems, including skin diseases, skeleton disorders, glucose intolerance and birth defects.
Isotopes of Manganese
There is one naturally occurring isotope of manganese, manganese-55. There are eighteen radioactive isotopes of manganese, with atomic masses ranging from 46 to 65. Among the radioactive isotopes, manganese-53 is the most stable and have a half-life of around 4 million years.
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