Calcuate the formal charge on each atom in `SO_(5)^(2-)` (per -oxosulphate ion) .

Explanation

Lewis structure of `SO_(5)^(2-)` ion is
(a) `FC` on `S`-atom
No of valence `e^(-)` on S-atom `=6 e^(-')s`
Lone pair (lp) electrons on S-atom `=0`
No of bond pair `e^(-')s` S-atom forms `=6 xx 2 = 12e^(-')s`
`FC` on S-atom `= 6 -0 - (1)/(2) xx (12) = 0`
(b) FC on Oatom (marked 1 and 5)
No of valence `e^(-)s` on Oatom `=3 xx 2 =6e^(-)`
No of bond pair `e^(-')s` on O-atom `=2e^(-)`
`FC` on O-atom (marked 1 and 5) `=6 -6 - (1)/(2) xx 2`
`[{:(,-1" on each"),(,"O-atom or-2"),(,"on both O-atoms"):}]`
`FC` on O-atom (marekd 2 and3) is
`6 -4 - (1)/(2) xx 4 = 0`
(d) `FC` on O-atom (marked4) is
`6 -4 (1)/(2) xx 4 =0`
Therefore, sum of `FC = 0 -2+0 = -2`
Net charge on `SO_(5)^(2-) = -2`
Hence, sum of `FC` Net charge on the ion
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