posted by Emily .
How come the charges of H*2O*2 (asterisk means subscript), which is hydrogen peroxide,don't equal? The charge of hydrogen is 2, and the charge of O is 4.
For an ionic compound you can figure out the formula by the charges(when the charges of the ions add up to zero) but does the method apply to molecular compounds too?
Not quite. The charges ARE equal.
H = +1 charge on each of 2 = 2 x 1 = +2
O = -1 charge on each of 2 = 2 x -1 = -2
Total = 0.
Why? Because oxygen has -2 oxidation state in OXIDES, in PEROXIDES the oxidation state is -1, In the free state oxygen is zero. Watch for hydrides. They have hydrogen of -1 and not +1 (NaH, LiH).