Oxidation State of Bromine in Barium Perbromate

Charge of Br in Ba(BrO4)2 ?

How do you figure it out considering the subscript 2 after the perbromate?

Ba = +2
Since there are 2 BrO4 ions, the charge on1 BrO4 ion is -1.

So, BrO4 = -1
O = -2, 4 O’s = -8

Br + -8 = -1
Br = +7


Br is in column 17 in the periodic table. Ions in this column have charge of -1 or +7.