![]() K) at 25✬ and 1 at 0.48 Thermal conductivity (W/cm.(✬) 1962 Earth's crust abundance (ppm) 950 Isotope (abundance %) 55Mn (100) Density (g/cm 3) 7.43 vdW radius (pm) 205 Covalent radius (pm) 129 Electronegativity (Pauling) 1.83 Vaporisation enthalpy (Kj/mol) 219.70 Fusion enthalpy (kJ/mol) 12.91 Specific heat capacity (J/g Symmary of properties (Mn) Atomic weight 54.938043(2) Discoverer (year) Gahn, Johan Gottlieb (1774) Natural form metallic solid (cubic centred) Electron configuration 3 d 5 4 s 2 M.p. These spectra are usefull to identify the elements present in a sample. This results in a characteristic emission line in the spectra (which corresponds to specific wavelengths of light). When an electron in an atom is excited to a higher energy level, it can de-excite by emitting a photon of light with an energy equal to the difference between the two levels. The orbitals are filled in a specific order, starting with the lowest energy orbital and working up.Įach element in the periodic table presents its own unique emission spectra, which is determined by the energy levels of its electrons. In the electron configuration notation, the letters "s", "p", "d", and "f" represent the different types of atomic orbitals, and the superscripts indicate the number of electrons in each orbital. The electron configuration of an element describes the arrangement of electrons in the atoms of that element, and be used to predict its chemical properties and reactivity. In this reaction, manganese begins in two different oxidation states and forms a product that exhibits an oxidation state intermediate between the two initial states. In acidic solution, permanganate also oxidizes the manganous ion (the “+2” state) to form manganese dioxide (the “+4” state), as shown in the following equation:ĢMnO 4 –(aq) + 3Mn 2+(aq) + 2H 2O(l) → 5MnO 2(s) + 4H +(aq) Where MnO 4 – is the purple-colored permanganate ion in which manga- nese is in the “+7” oxidation state. The manganate ion (MnO 4 2-) disproportionates in acidic solution to the “+4” and “+7” states, as shown in the following reaction:ģMnO 4 2-(aq) + 4H+(aq) → MnO 2(s) + 2MnO 4 – (aq) + 2H 2O(l) In higher oxidation states, oxides of manganese are acidic because they dissolve in basic solutions. ![]() Manganese dioxide is amphoteric because it is soluble in both acid and basic solutions. In the “+4” state, manganese forms black manganese dioxide (MnO 2), which is the only compound of manganese (IV). The oxides formed in the “+2” and “+3” states (manganous oxide (MnO) and manganic oxide (Mn 2O 3), respectively) are bases due to their solubility in acid solutions, as shown in the following example: The manganic ion (Mn 3+) tends to be unstable in aqueous solution and disproportionates into Mn(II) and Mn(IV), as shown in the following reaction:ĢMn 3+(aq) + 2H 2O(l) → Mn 2+(aq) + MnO 2(s) + 4H +(aq)ĭisproportionation means that an element initially in only one oxidation state changes to two products: one product exhibiting a lower oxidation state and the other exhibiting a higher state. Examples of manganese in these states are illus- trated in the following series: Mn «0» Mn 2+ «+2» Mn 3+ «+3» MnO 2 «+4» MnO 3 – «+5» MnO 4 2-«+6» MnO 4 – «+7».Īs it is in group VIIA, its “+7” oxidation state is the preferred one. In compounds, manganese can be in any of the oxidation states from “+2” to “+7,” inclusive. ![]() For example, in hydrochloric acid, the following reaction takes place: Manganese metal is readily oxidized in the presence of oxygen gas, water, and hydrochloric acid. Manganese is an essential element in animals: it increases bone strength, helps absorb vitamin B1 and is an important cofactor for enzymes. Manganese is also a component of certain enzymes, and it is also used in the production of fertilizers and other chemicals, and in the manufacturing of ceramics and glass. ![]() In prehistoric times, manganese dioxide, MnO 2, was crushed to make the dark colors used in cave paintings. Manganese compounds are also added to gasoline and are used to clean impurities from glass to lighten it or give it a purple color. Certain dry cell batteries carry a mixture containing manganese oxide. Applications of manganese include its use in strengthening steel, which is used in the manufacture of railroad tracks and tank armor. The human body needs a small amount of manganese, which we can obtain from mussels, nuts, oats and pineapples. This element is present in seawater in the form of manganese hydroxide and manganese oxide, which have accumulated in layers over millions of years to form masses on the seabed. Pure manganese is dense, hard and brittle. The pure form of the metal is obtained mainly from the pyrolusite mineral, through a process called electrolysis. Manganese, like magnesium, is named after the Greek region of Magnesia, where there are many manganese ores, including the colorful rodochrosite mineral. Manganese is a chemical element with the symbol Mn and atomic number 25. ![]()
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