The,nature,the,manganese,The,p business, insurance The nature of the manganese
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The physical properties of the manganese, manganese is a cubic crystal, has±, ², ³ and ´ four kinds allotropic body, in ambient temperature, the ±manganese is the most stable. Mechanical properties of manganese is hard andbrittle, Mohs hardness is 5 to 6, the dense block manganese metal surface is silver-white,powdery is gray. The relative atomic weight of manganese is 54.9380 ± 1. Atomicvolume is 7.39cm3/mol.The density of manganese atomic radius and at room temperature are slightlydifferent with the different polymorphs, at room temperature, the atomic radiusof manganese, density, are related to the polymorph.Manganese is a reactive metal, susceptibleto be oxidized. Manganese powder is easyto burn in air, but large massive metallic manganese is uneasy to be oxidizedin the air erosion at ambient temperature, this is because the manganese metalsurface in the air easy to generate a layer of oxide film, play a protectiverole on the inner metallic manganese. In water, it is easy to generatehydroxide film, and can further prevent the manganese on the replacement of thehydrogen in the water molecules. Due to the electrons in the outermost layerand the second outer (3d4s) can become a valence electron, so that manganese isan element of the price change. Manganese oxidation state have +2, +3, +4, +6and +7. Valence of changes lead to changes in the ionic nature, such as theradius of the manganese ions smaller with a valence higher, ion potential andelectrically negative increased with the valence increases correspondingly, thepH of their oxides with increased valence by alkaline to acidic changes. Homologousacid-base properties of oxide and hydrate of manganese is the most typical inthe transition elements. It manifested that with the oxidation state of manganese,alkaline gradually weakened, acidic gradually increased.Covalent radius of manganese is 117pm, thesame as the covalent radius of the iron and copper; similar with the covalentradius of the chrome, diamond, nickel. Manganese belonging to the fourth periodof the transition elements, compared with Sc, Ti, V, Cr, Fe, Co, Ni, especiallycompared with adjacent Cr and Fe, Mn has some special physical and chemicalproperties. These characteristics are with great significance for understandingthe geochemical characteristics of manganese. The atomic radius of thetransition elements in the fourth cycle, the general trend from Sc to Ni withthe atomic number increases sequentially reduced, and only manganese is anexception. Its atomic radius is 136.6pm (³-Mn), larger than Cr (124.9pm) and Fe(124.1pm), undermining the law of diminishing. The fourth period transition inthe oxidation state of the element, only the manganese has the highest +7oxidation state. Transition elements before manganese (Sc of Cr) highestoxidation state is gradually increased from +3 to +6; transition elements aftermanganese (Fe to Ni) the highest oxidation state is gradually reduced from +6to +3. The oxidation state of the transition elements before manganese increasesis related to the increase number of valence electrons in the 3d orbitals. Whenthe number of electrons in the 3d orbitals up to more than 5 (from Cr to Ni) 3dorbit gradually moving towards stability and high oxidation state graduallyunstable, showing strong oxidizing gradually reduce the oxidation state of thetransition elements manganese. In the fourth period transition element,manganese has the lowest melting point and boiling point. From Sc to of Cr, themelting point is 1539 ~ 1890,boiling point is 2483 to 3380;from Fe to Ni, the melting point is 1453 to 1535,the boiling point is 2732 to 3000and manganese melting point is 1260,boiling point is 2077 its meltingheat and heat of vaporization is also low. The standard electrode potential ofthe transition elements of the fourth cycle, substantially from Sc to Niincreases gradually. And their metallic weakened is consistent. But onlymanganese standard electrode potential is lower than chromium, undermining thelaw of this increment. Thus, manganese in the fourth cycle transition elements,has its unique physical and chemical properties.Source:http://www.mhcmp.com
The,nature,the,manganese,The,p