Transition elements
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My investigation is about manganese in tea and I have found out that the reason that the purple colour is due to charge transfer. I have tried looking on the internet but i am still very confused. Can you please explain it to me and also is charge transfer the reason for the colour seen from the oxidation of Fe2+ to Fe3+ in iron in tea?
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Ulex writes
The explanations of the origins of colour in chemical species is a bigger place than I have the chance to explore fully here. Most colours arise because a process absorbs some frequencies from white light, leaving others which are what we see. The most common processes are electronic transitions – movements of electrons either from place to place within the species or from lower to higher energy levels within particular atoms or ions.
The latter kind are normally between d orbitals which have been split into groups because of complexing. Such transitions result in pale colours such as the green of Fe2+ (aq) or the yellow of Fe3+ (aq).
The former kind, the charge transfer type, tend to give strong colours such as the tetrammine copper(II) ion or the purple of MnO4-.
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updated: 11 April 2008
