| Discovery date | 1774 |
| Discovered by | Johan Gottlieb Gahn |
| Origin of the name | The derivation of Manganese may have come from one of two routes: either from the Latin 'magnes', meaning magnet, or from the black magnesium oxide, 'magnesia nigra'. |
| Allotropes |
|
Mn
Manganese
25
54.938
| Group | 7 | Melting point | 1246°C, 2275°F, 1519 K |
| Period | 4 | Boiling point | 2061°C, 3742°F, 2334 K |
| Block | d | Density (g cm−3) | 7.3 |
| Atomic number | 25 | Relative atomic mass | 54.938 |
| State at 20°C | Solid | Key isotopes | 55Mn |
| Electron configuration | [Ar] 3d54s2 | CAS number | 7439-96-5 |
| ChemSpider ID | 22372 | ChemSpider is a free chemical structure database | |
Image explanation
The image is of an antique electromagnet and a cow. The electromagnet is because manganese may have got its name from the Latin word for magnet. The cow reflects the importance of the element as a food supplement for grazing animals.
Appearance
A hard, brittle, silvery metal.
Uses
Manganese is too brittle to be of much use as a pure metal. It is mainly used in alloys, such as steel.
Steel contains about 1% manganese, to increase the strength and also improve workability and resistance to wear.
Manganese steel contains about 13% manganese. This is extremely strong and is used for railway tracks, safes, rifle barrels and prison bars.
Drinks cans are made of an alloy of aluminium with 1.5% manganese, to improve resistance to corrosion. With aluminium, antimony and copper it forms highly magnetic alloys.
Manganese(IV) oxide is used as a catalyst, a rubber additive and to decolourise glass that is coloured green by iron impurities. Manganese sulfate is used to make a fungicide. Manganese(II) oxide is a powerful oxidising agent and is used in quantitative analysis. It is also used to make fertilisers and ceramics.
Biological role
Manganese is an essential element in all known living organisms. Many types of enzymes contain manganese. For example, the enzyme responsible for converting water molecules to oxygen during photosynthesis contains four atoms of manganese.
Some soils have low levels of manganese and so it is added to some fertilisers and given as a food supplement to grazing animals.
The average human body contains about 12 milligrams of manganese. We take in about 4 milligrams each day from such foods as nuts, bran, wholegrain cereals, tea and parsley. Without it, bones grow spongier and break more easily. It is also essential for utilisation of vitamin B1.
Natural abundance
Manganese is the fifth most abundant metal in the Earth’s crust. Its minerals are widely distributed, with pyrolusite (manganese dioxide) and rhodochrosite (manganese carbonate) being the most common.
The main mining areas for manganese are in China, Africa, Australia and Gabon. The metal is obtained by reducing the oxide with sodium, magnesium or aluminium, or by the electrolysis of manganese sulfate.
Manganese nodules have been found on the floor of the oceans. These nodules contain about 24% manganese, along with smaller amounts of many other elements.
Manganese in the form of the black ore pyrolucite (manganese dioxide, MnO2) was used by the pre-historic cave painters of the Lascaux region of France around 30,000 years ago. In more recent times was used by glass makers to remove the pale greenish tint of natural glass.
In 1740, the Berlin glass technologist Johann Heinrich Pott investigated it chemically and showed that it contained no iron as has been assumed. From it he was able to make potassium permanganate (KMnO4), one of the strongest oxidising agents known. Several chemists in the 1700s tried unsuccessfully to isolate the metal component in pyrolusite. The first person to do this was the Swedish chemist and mineralogist Johan Gottlieb Gahn in 1774. However, a student at Vienna, Ignatius Kaim, had already described how he had produced manganese metal, in his dissertation written in 1771.
| Atomic radius, non-bonded (Å) | 2.05 | Covalent radius (Å) | 1.29 |
| Electron affinity (kJ mol−1) | Not stable |
Electronegativity (Pauling scale) |
1.55 |
|
Ionisation energies (kJ mol−1) |
1st
717.274
2nd
1509.03
3rd
3248.468
4th
4940
5th
6985.5
6th
9224
7th
11501.342
8th
18766.4
|
||
| Common oxidation states | 7, 6, 4, 3, 2, 0, -1 | ||||
| Isotopes | Isotope | Atomic mass | Natural abundance (%) | Half life | Mode of decay |
| 55Mn | 54.938 | 100 | - | - | |
|
|
|
Specific heat capacity (J kg−1 K−1) |
479 | Young's modulus (GPa) | Unknown | |||||||||||
| Shear modulus (GPa) | Unknown | Bulk modulus (GPa) | 118 | |||||||||||
| Vapour pressure | ||||||||||||||
| Temperature (K) |
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| Pressure (Pa) |
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| Listen to Manganese Podcast |
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Transcript :
Chemistry in its element: manganese(Promo) You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry. (End promo) Chris Smith Hello! This week to the element that lies at the root of plant photosynthesis, fights free radicals, strengthens steel, makes mysterious ocean floor nodules and even goes to mix up with magnesium. Here's Ron Caspi. Ron Caspi I always feel that manganese is sadly overlooked. It's the fifth most abundant metal in the Earth crust and the second most abundant transition metal after iron, but say, manganese and many people will think of the much more familiar magnesium. There is a good reason why the names of these two elements are so confusingly similar, but we'll get to that in a minute. There are more than 300 different minerals that contain manganese. Large terrestrial deposits are found in Australia, Gabon, South Africa, Brazil and Russia. Yet more fascinating are the mysterious three trillion tons of manganese nodules that cover great parts of the ocean floor. These nodules are never covered by the constantly accumulating sediment. They manage to always stay above the sediment, due to the constant pushing and turning by their keepers, the small animals that live on the ocean floor. Almost half a billion dollars were invested in developing mining techniques for the nodules, but they're found so deep, mostly at depth of 4 to 6 kilometres, that the mining is still not commercially viable. Manganese is an extremely versatile element. It can exist in six different oxidation states. In nature, it is usually found in either its reduced +2 state, which easily dissolves in water or in the +4 state, which forms many types of insoluble oxides. The +3 form of manganese is used as a powerful weapon, by dry rot fungi that break down wood. Wood contains a lot of lignin, a polymer that is almost indestructible by biological systems; indestructible that is unless you use manganese. A fungal enzyme, manganese peroxidase, oxidizes manganese +2 atoms to manganese +3, which are then sent to the tiny spaces within the wood lattice. Manganese +3 is highly reactive and can break down the chemical bonds of lignin, making it available as food for the fungus. Fungi are not the only organisms that harness the power of manganese chemistry. Manganese is an essential element for all life forms. It is absolutely necessary for the activity of several enzymes that must bind a manganese atom before they can function, including superoxide dismutase, an enzyme that protects us from the harmful effects of toxic oxygen radicals. One of the most important reactions in biology, photosynthesis, is completely dependent on manganese. It is the star player in the reaction centre of photosystem II where water molecules are converted to oxygen. Without manganese, there would be no photosynthesis as we know it and there would be no oxygen in the atmosphere. While biology discovered manganese early on, it took humankind a bit longer. Already in ancient Egypt, glass blowers who got tired of their greenish glass founded by adding small amounts of certain minerals to the mix, they could make perfectly clear glass. They didn't realize it at that time, but these minerals, which were affectionately named, Sapo vitri or glass soap were manganese oxides. Excellent ores were found in the region of Magnesia, the region of northern Greece, just south of Macedonia, and this is how the trouble with manganese names started. Different ores from the region, which included both magnesium and manganese, were simply called magnesia. In the 1600s, the term magnesia alba or white magnesia was adopted for magnesium minerals, while magnesia nigra or black magnesia was used for the darker manganese oxides. By the way, the famous magnetic minerals that were discovered in that region were named Lapis magnis or stone of magnesia, which eventually became today's magnet. For a while, there was a total mix up concerning manganese and magnesium, but in the late 18th Century, a group of Swedish chemists, headed by Torbern Bergman were convinced that manganese is its own element. In 1774, Scheele, a member of the group presented these conclusions to the Stockholm Academy and later that year, Johann Gahn, another member became the first man to purify manganese and prove that it is an element. It took a few more years, but by 1807, the name manganese was accepted by all. Today, manganese is used for countless industrial purposes. By far, the most important one is in steel making. When Sir Henry Bessemer invented the process of steel making in 1856, his steel broke up when hot rolled or forged; the problem was solved later that year, when Robert Foster Mushet, another Englishman, discovered that adding small amounts of manganese to the molten iron solves the problem. Since manganese has a greater affinity for sulphur than does iron, it converts the low-melting iron sulphide in steel to high-melting manganese sulphide. Since then, all steel contains manganese. In fact, about 90% of all Manganese produced today, is used in steel. From the mysterious nodules at the bottom of the ocean to the decay of wood, from ancient glassblowing to modern steel-making, from fighting oxygen radicals to photosynthesis, manganese has always played a fascinating role in the chemistry, geology, and biology of our planet, a role that is seriously under appreciated. Chris Smith Ron Caspi. Next time, to a cheeky chemical with some practical and also some less than practical uses that is unless you're a practical joker. Andrea Sella Alloys containing bismuth were used for safety valves and boilers, melting if the temperature rose too high and a classic prank invented in Victorian times was to cast spoons from an alloy consisting of 8 parts bismuth, 5 parts lead and 3 parts tin. Its melting point is low enough for the spoon to vanish into a cup of hot tea to the astonishment of the unsuspected visitor. Chris Smith Andrea Sella, who'll be revealing the story of bismuth on next week's Chemistry in its element. I hope you can join us. I am Chris Smith, thank you for listening and goodbye! (Promo) Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists.com. There's more information and other episodes of Chemistry in its element on our website at chemistryworld.org/elements. (End promo)
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Visual Elements images and videos
© Murray Robertson 1998-2017.
W. M. Haynes, ed., CRC Handbook of Chemistry and Physics, CRC Press/Taylor and Francis, Boca Raton, FL, 95th Edition, Internet Version 2015, accessed December 2014.
Tables of Physical & Chemical Constants, Kaye & Laby Online, 16th edition, 1995. Version 1.0 (2005), accessed December 2014.
J. S. Coursey, D. J. Schwab, J. J. Tsai, and R. A. Dragoset, Atomic Weights and Isotopic Compositions (version 4.1), 2015, National Institute of Standards and Technology, Gaithersburg, MD, accessed November 2016.
T. L. Cottrell, The Strengths of Chemical Bonds, Butterworth, London, 1954.
John Emsley, Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, New York, 2nd Edition, 2011.
Thomas Jefferson National Accelerator Facility - Office of Science Education, It’s Elemental - The Periodic Table of Elements, accessed December 2014.
Periodic Table of Videos, accessed December 2014.
Derived in part from material provided by the British Geological Survey © NERC.
Elements 1-112, 114, 116 and 117 © John Emsley 2012. Elements 113, 115, 117 and 118 © Royal Society of Chemistry 2017.
Produced by The Naked Scientists.
Created by video journalist Brady Haran working with chemists at The University of Nottingham.
© Murray Robertson 1998-2017.
Data
W. M. Haynes, ed., CRC Handbook of Chemistry and Physics, CRC Press/Taylor and Francis, Boca Raton, FL, 95th Edition, Internet Version 2015, accessed December 2014.
Tables of Physical & Chemical Constants, Kaye & Laby Online, 16th edition, 1995. Version 1.0 (2005), accessed December 2014.
J. S. Coursey, D. J. Schwab, J. J. Tsai, and R. A. Dragoset, Atomic Weights and Isotopic Compositions (version 4.1), 2015, National Institute of Standards and Technology, Gaithersburg, MD, accessed November 2016.
T. L. Cottrell, The Strengths of Chemical Bonds, Butterworth, London, 1954.
Uses and properties
John Emsley, Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, New York, 2nd Edition, 2011.
Thomas Jefferson National Accelerator Facility - Office of Science Education, It’s Elemental - The Periodic Table of Elements, accessed December 2014.
Periodic Table of Videos, accessed December 2014.
Supply risk data
Derived in part from material provided by the British Geological Survey © NERC.
History text
Elements 1-112, 114, 116 and 117 © John Emsley 2012. Elements 113, 115, 117 and 118 © Royal Society of Chemistry 2017.
Podcasts
Produced by The Naked Scientists.
Periodic Table of Videos
Created by video journalist Brady Haran working with chemists at The University of Nottingham.
