MnO4-

[Delaney Smith 1C]

Why is the charge of MnO4- +7?

[Tiffany_Chen 2K]

Oxygen has a -2 charge for each atom, given a total of -8 charge. Since the overall molecule is -1, Mn will have to be +7.

[haileyramsey-1c]

Since oxygen always has an oxidation number of 2- it determines the oxidation number of the other atoms present. In this case in order for overall charge to be 1-, Mn must be 7+.

[Deena Doan 2F]

The overall molecule has a charge of -1 and we already know that oxygen has a charge of -2 and when you multiply by 4, you get a charge of -8. So, in order to get that -1 charge, Mn has to have a 7+ charge.

[205291012]

MnO4-

Let the charge of Mn = x.
Charge of O= -2
Overall charge = -1

x + (-2*4) = -1
x - 8 = 1
x = -1+8
x = +7

[Max Madrzyk Dis 4G]

The charge of Mn is 7+ because O has a charge of 2- and there are 4 of them making a total charge of 8-. We are then told that the overall charge of the molecule is 1- so we know that Mn must have a 7+ charge to get the total charge to equal 1-.