What is the oxidation number for Mn in Mn2O7? (provide sign and number)

The oxidation number of the elements should be equal to zero or the charge of the compound when summed together. In this case, the overall charge is zero. Oxygen has a charge of - 2, hence the magnesium ion should have a charge of + 7 in order for the overall charge to be equal to zero

Answer;

+7

Explanation;

The sum of the oxidation numbers of all of the atoms in a neutral compound is 0. The sum of the oxidation numbers in a polyatomic ion is equal to the charge of the ion. In this case the overall oxidation number is Zero.

Thus; Oxidation number of oxygen is - 2

Mn2O7; has 2 manganese atoms and 7 oxygen atoms;

= (2 * y) + (7 * - 2) = 0

= 2y = 14

y = + 7

Oxidation number of Mn in Mn2O7 is + 7