Final answer:
The charge of the manganese cation can be deduced from the compound's formula and name by balancing the total charge. For example, in permanganate (MnO4), the manganese cation has a +7 charge to balance four -2 oxygen anions and result in the compound's overall -1 charge.
Step-by-step explanation:
The charge of the manganese cation in a compound can be determined from the name of the compound. For instance, in the permanganate ion (MnO4), with an overall -1 charge, and the oxidation state of each oxygen being -2, the manganese cation has an oxidation state of +7. This is because the four oxygen atoms contribute a total of -8 in charge, and to balance a -1 charge, the manganese must have +7 charge.
In another example, the iron compound FeCl2 has two chloride anions each with a -1 charge, therefore the iron cation must be +2 to balance the -2 charge, resulting in the Fe²+ ion. Similarly, Mn₂O3 features manganese in a +3 oxidation state, known as manganese(III) oxide. In MnO₂, the manganese has an oxidation state of +4, hence it is called manganese(IV) oxide.