Why is the permanganate ion so intensely coloured

The permanganate ion, MnCU-, has a beautiful, intense purple colour, and is a popular choice for oxidation reactions. The colour is intense even if the solution is dilute. 

Care don t confuse Group VII(a) (manganese, technetium and rhenium) with Group VII(b), the halogens. 

Care we write a formal charge with Arabic numerals, and means that the full charge exists as indicated Cu2+ means a copper atom with fully two electronic charges missing. We write an oxidation number with Roman numerals, and does not relate to any physical loss or gain of electrons it is purely a book-keeping exercise. Mnvn does not mean that a manganese atom has lost seven electrons. 

The small increment of charge S might be as small as 0.1 electronic charges. 

The system relaxes back to the starting materials (the reverse of Equation (9.16)) within a tiny fraction of a second. 

---