| Manganese - Mn
CAS: 7439-96-5 Description: Silver-gray metal with a pinkish tinge Classification: Transition Metal Date of Discovery: 1774 Discoverer: Johann Gahn Name Origin: Latin mangnes (magnet), from magnetic properties of pyrolusite; Italian manganese, corrupt form of magnesia |
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Atomic Number: 25
Number of Neutrons: 30 Atomic Mass: 54.93805(1) amu Melting Point: 1246 ± 3 °C Boiling Point: 2061.0 °C Density (293 K): 7.21 to 7.44 g/cm3depending on allotropic form Atomic volume: 1.39 cm³/mol Electrical resistivity: 0.00695 10-6/cm 
Thermal conductivity: 0.0782 W/cmK Enthalpy of atomization: 280.33 kJ/mol Enthalpy of vaporization: 226.0 kJ/mol Enthalpy of fusion: 12.050 kJ/mol Specific heat capacity: 0.48 J/gK |
Energy levels: 2-8-13-2
Electron configuration: [Ar]3d54s2 Crystal Structure: Cubic body centered Atomic radius: 1.79 Å Covalent radius: 1.17 Å Oxidation States: +1, +2, +3, +4, +6, +7 Electronegativity, Pauling: 1.55 Electron affinity: not stable First ionization energy: 7.435 eV 2nd ionization energy: 15.64 eV 3rd ionization energy: 33.667 eV Polarizability: 9.4 10-24cm3 |
| Isotope | Natural Abundance | Atomic Mass | Half-life | Decay Mode | Spin |
| 46Mn | 45.9867 |  41 ms |
 + |
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| 47Mn | 45.9761 | + |
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| 48Mn | 47.9686 | 0.15 s | + |
4+ | |
| 49Mn | 48.95962 | 0.38 s | + |
5/2- | |
| 50mMn | 1.74 m | + |
5+ | ||
| 50Mn | 49.954244 | 0.283 s | + |
0+ | |
| 51Mn | 50.948215 | 46.2 m | +, EC |
5/2- | |
| 52mMn | 21.1 m | +; IT |
2+ | ||
| 52Mn | 51.945 | 5.591 d | +; EC |
6+ | |
| 53Mn | 52.941294 | 3.7 x 106 y | EC | 7/2- | |
| 54Mn | 53.940363 | 312.2 d | EC | 3+ | |
| 55Mn | 100. | 54.938049 | Stable | 5/2- | |
| 56Mn | 55.938909 | 2.579 h | - |
3+ | |
| 57Mn | 56.938287 | 1.45 m | - |
5/2- | |
| 58Mn | 57.93999 | 65 s | - |
3+ | |
| 59Mn | 58.94045 | 4.6 s | - |
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| 60mMn | 1.77 s | -; IT |
3+ | ||
| 60Mn | 59.9433 | 50 s | - |
0+ | |
| 61Mn | 60.9446 | 0.71 s | - |
(5/2-) | |
| 62Mn | 61.9480 | 0.9 s | - |
(3+) | |
| 63Mn | 62.9498 | - |
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| 64Mn | 63.9537 | - |
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| 65Mn | 64.956 | - |
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| 66Mn | |||||
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Recognized by Scheele, Bergman, and others as an element and isolated by Gahn in 1774 by reduction of the dioxide with carbon. Manganese minerals are widely distributed; oxides, silicates, and carbonates are the most common. the discovery of large quantities of manganese nodules on the floor of the oceans holds promise as a source of manganese. These nodules contain about 24% manganese together with many other elements in lesser abundance. Most manganese today is obtained from ores found in Russia, Brazil, Australia, Republic of S. Africa, Gabon, and India. Pyrolusite (MnO2) and rhodochrosite (MnCO3) are among the most
common manganese minerals. Psilomelane [(BaH2O)2Mn5O10], although not as common as pyrolusite, is still an important ore of manganese. The mining term "wad" is used to indicate ores that are a mixture of several manganese oxides such as psilomelane, pyrolusite and others that are difficult to distinguish. The metal is obtained by reduction of the oxide with sodium, magnesium, aluminum, or by electrolysis. It is gray-white, resembling iron, but is harder and very brittle. The metal is reactive chemically, and decomposes cold water slowly. Manganese is used to form many important alloys. In steel, manganese improves the rolling and forging qualities, strength, toughness, stiffness, wear resistance, hardness, and hardenability. With aluminum and antimony, especially with small amounts of copper, it forms highly ferromagnetic alloys. Manganese metal is ferromagnetic only after special treatment. The pure metal exists in four allotropic forms. The alpha form is stable at ordinary temperature; gamma manganese, which changes to alpha at ordinary temperatures, is said to be flexible, soft, easily cut, and capable of being bent. The dioxide (pyrolusite) is used as a depolarizer in dry cells, and is used to "decolorize" glass that is colored green by impurities of iron. Manganese by itself colors glass an amethyst color, and is responsible for the color of true amethyst. The dioxide is also used in the preparation of oxygen and chlorine, and in drying black paints. The permanganate is a powerful oxidizing agent and is used in quantitative analysis and in medicine. Manganese is widely distributed throughout the animal kingdom. It is an important trace element and may be
essential for utilization of vitamin B1. Twenty-three isotopes and isomers are known.
LINKS: EcoIndiana - Toxicological Profile for Manganese The Importance of Manganese Manganese and water quality Manganese Sequestering USGS - Manganese Statistics and Information Origin of Manganese in Cigarette Smoke and Ash Return
Sources for the information on this website include: Lide, David R., ed. CRC Handbook of Chemistry and Physics, 78th Ed., 1997-1998. |
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