Manganese oxidation levels

Figure 2. Alpha spectrum for a radium adsorbing manganese-oxide thin film exposed to a groundwater sample, after Surbeck (2000) and Eikenberg et al. (2001b). A 2x2 cm sheet is exposed to O.l-l.O L of sample for 2 days, capturing nearly all of the radium in the sample. These sample discs can be used directly for low-level alpha spectrometry without the need for further separation and preparation methods to produce planar sample sources. Energy resolution is nearly as good as for electroplated sources, and detection limits are typically 0.2 mBqA (6 fg Ra/L) for Ra and " Ra for a one-week counting period. These sensitivities are comparable to traditional methods of alpha spectrometry. [Used by permission of Elsevier Science, from Eikenberg et al. (2001), J Environ Radioact, Vol. 54, Fig. 4, p. 117]...

Manganese represents the epitome of that characteristic property of the transition element namely the variable oxidation state. The aqueous solution chemistry includes all oxidation states from Mn(II) to Mn(VII), although these are of varying stability. Recently attention has been focused on polynuclear manganese complexes as models for the cluster of four manganese atoms which in conjunction with the donor side of Photosystem(II) is believed involved in plant photosynthetic oxidation of water. The Mn4 aggregate cycles between 6 distinct oxidation levels involving Mn(II) to Mn(IV). 

Reduction is defined as the gain of electrons. The conversion of Ag1+ —> Ag° involves a gain of an electron by file silver ion and thus silver is reduced. Likewise, file permanganate ion Mn( )4 has MnfVII] but MnC>2 manganese dioxide has Mn[IV]. Thus file gain of three electrons by manganese causes a reduction in oxidation level of from +7 to +4. 

Considering all of the manganese catalases together, there have been four cluster oxidation levels that are established Mn(II,II), Mn(II,III), Mn(III,III), and Mn(III,IV). The as-isolated enzyme contains a mixture of these states. The Mn(II,II) enzyme can be prepared by the addition of hydroxylamine to the isolated enzyme. If hydrogen peroxide is added to this sample, without removing the hydroxylamine, the enzyme is converted to the Mn(III,IV) form however, if the hydroxylamine is first... 

Make a diagram listing compounds representative of die various important oxidation levels of chromium and manganese. 

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