Manganese (Mn) is the 25th chemical element on the periodic table – that is, its atoms have 25 protons in their nucleus. A naturally occurring metal, manganese is often used in industrial alloy processing and as a rust prevention tool.
– Chemical Properties –
Manganese has a grey or silverish appearance. Unlike some other metals, it tends to be quite brittle. Only a single stable isotope of manganese is known to occur in nature, manganese-55. Beyond that, a considerable number of radioactive isotopes exist, and one, manganese-53, has a half-life estimated to be several million years.
Manganese, like iron, is believed to have been ejected from large, dying stars. So long as iron is exposed to high radiation, such as from unshielded cosmic rays, small amounts of manganese-53 will be continuously produced. It is assumed, therefore, that the various radioactive isotopes of manganese which can be produced today were once present on Earth and the other planets in considerable amounts, but have long since decayed away, until virtually none remained.
Like a number of other metals, manganese can form a variety of different compounds depending upon the degree to which its atoms are ionized – that is, how many electrons they surrender to atoms on the right block of the periodic table, such as oxygen and chlorine. In most cases, manganese surrenders just two electrons, forming chemicals such as manganese sulphate and rhodochrosite (a mineral also known by its formal chemical name, manganese carbonate). Under certain conditions, manganese can be forced to surrender up to seven electrons, at which time it forms purple-coloured compounds called “permanganates.”
– Uses –
Manganese make up about a tenth of a percent of the Earth’s solid surface, occurring only in minute trace amounts in most areas and found principally as a component of minerals such as rhodochrosite, braunite, and, especially, pyrulosite. Manganese mining and extraction currently occurs only in a half-dozen major centres worldwide, and just two countries, South Africa and the Ukraine, produce the vast majority of our current stocks.
In addition, large amounts of manganese are known to lie deposited on the ocean floor, which spurred the first major generation of research into deep-sea mining technology during the 1970s. Although the current ‘Law of the Sea’ was negotiated to make provision for this sort of mining, the research and development projects eventually concluded that there was no economically viable method of extracting manganese from the ocean floor with current technology.
Once extracted and processed, manganese is principally used in hardening various steel and other metal alloys, as well as in making batteries. (However, manganese is now essentially obsolete following the rise of lithium batteries.) A complex organic compound which contains manganese is also used as a gasoline additive to prevent engine knocking, after the elimination of leaded gasoline in the 1970s.
Trace amounts of manganese are found within the body. However, along with similar elements like nickel, manganese can be toxic to humans, causing various mental conditions or, at sufficiently high levels, even death. Manganese miners sometimes suffer from a related degenerative mental disease called manganism, with symptoms similar to the better-known chronic condition Parkinson’s disease.
– Discovery –
The ancient Greeks knew two metal compounds called “magnes”, so named because they had mild magnetic powers when in the presence of iron (what the Greeks, in turn, would have called by the older term lodestone). One was used in glass; the other, in magnets. The glass chemical later came to be known as manganesum by glass-smiths and alchemists, which was eventually shortened to simply manganese. However, it was not until the late 18th century that the early chemists were able to isolate and identify the element manganese, separate from the manganese oxides used by the glassmakers.
In the more distant past, manganese compounds are known to have been used due to their pigment, in ancient cave paints as early as the Stone Age.