Science / Periodic Table of Elements / Manganese (Mn): Atomic number: 25, Atomic mass: 54.9380 g.mol -1, Electronegativity: 1.5, Density: 7.43 g.cm-3 at 20°C, Melting point: 1247 °C, Boiling point: 2061 °C, Vanderwaals radius: 0.126 nm, Ionic radius: 0.08 nm (+2) ; 0.046 nm (+7), Isotopes: 7, Electronic shell: [ Ar ] 3d5 4s2, Energy of first ionisation: 716 kJ.mol -1, Energy of second ionisation: 1489 kJ.mol -1, Standard potential: - 1.05 V ( Mn2+/ Mn ), Discovered: Johann Gahn in 1774. Manganese is a pinkinsh-gray, chemically active element. It is a hard metal and is very brittle. It is hard to melt, but easily oxidized. Manganese is reactive when pure, and as a powder it will burn in oxygen, it reacts with water (it rusts like iron) and dissolves in dilute acids. Applications: Manganese is essential to iron and steel production. At present steel making accounts 85% to 90% of the total demand, most of the total demand. Manganese is a key component of low-cost stainless steel formulations and certain widely used alumimum alloys. Manganese dioxide is also used as a catalyst. Manganese is used to decolorize glass and make violet coloured glass. Potassium permanganate is a potent oxidizer and used as a disinfectant. Other compound that find application are Manganese oxide (MnO) and manganese carbonate (MnCO3): the first goes into fertilizers and ceramics, the second is the starting material for making other manganese compounds. Manganese in the environment: Manganese is one of the most abundant metals in soils, where it occurs as oxides and hydroxides, and it cycles through its various oxidation states. Manganese occurs principally as pyrolusite (MnO2), and to a lesser extent as rhodochrosite (MnCO3). More than 25 million tonnes are mined every year, representing 5 million tons of the metal, and reserves are estimated to exeed 3 billion tonnes of the metal. The main mining areas for manganese ores are South Africa, Russia, Ukraine, Georgia, Gabon and Australia. Manganese is an essential element for all species. Some organisms, such as diatoms, molluscs and sponges, accumulate manganese. Fish can have up to 5 ppm and mammals up to 3 ppm in their tissue, although normally they have around 1 ppm.
Science / Tides and Currents / Mean Range Of Tide (Mn): The difference in height between mean high water and mean low water. MORE
Science / Geology / Manganese Nodule: A rounded concretion, rich in manganese minerals with minor concentrations of cobalt, copper and nickel. These occur in abundance on some parts of the deep ocean floor and have been considered as a po MORE