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Kevin Wilkinson

Why is MnO4 a permanganate ion but MnO4(2-) is a manganate ion?

Amelia Noah  Follow

In both cases, ligand to metal charge transfer takes place due to high positive oxidation state of the metal. In MnO4- ion, Mn is in +7 oxidation state and in CrO42-, Cr is in +6 oxidation state.

So more charge is transferred from oxygen to Mn7+ ion than that to Cr+6 ion. This is the reason.

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Kollol Hossan  Follow

The permanganate ion is not neutral, it has a -1 charge. The “per” prefix is part of the naming system for oxoanions and refers to the oxidation state of the Manganese in the ion.

Permanganate: [math]MnO_4^-[/math] has Mn with an oxidation state of 7+

Manganate: [math]MnO_4^{2-}[/math] has Mn with an oxidation state of 6+

hypomanganate: [math]MnO_4^{3-}[/math] has Mn with an oxidation state of 5+.

The prefix “per”, means “above” or “higher” and we see the oxidation state of manganese in permanganate is higher (more positive) than in manganate.

The prefix “hypo” (think hypodermic needle), means “under” of “below” and we see that the oxidation state of the Manganese in hypomanganate is lower (less positive) than in manganate.

The oxidation state in manganate is considered to be the most common state for manganese and so is the basis of this naming scheme.

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