Question

3. Lewis structures of two chemical species are shown below. For each, give (i) the formal charge on each atom and (ii) the overall charge on each species. Structure a Structure b :: :: :00 н Atom 1 Atom 2 Atom 3 Atom 4 Atom 5 Оа Ob Oc

Answer 1

The formal charge on an atom in a Lewis formula is the hypothetical charge acquired by the atom assuming equal sharing of bonding electrons and complete possession of non bonding electrons , if any.. The formal charge is calculated as follows: Formal charge = ni-(net no riveno, of valence electrons of the free atomi n = no, of lone pair electrons. (no. of nonbonding electrons) nba no. of electrons forming bonds with other. Structure-a. : oa: is formal charge & elaleulation. I For el 7 nua 7. no:8 n=2 at has four bonds, each bond containing 2 electrons. 3. Formal charge on erz. 7-(2+) = 7 - (2+4)* : S. 7-6 =+1.

.. for Oa nu = 6, ne=6, no=2 (one bond, as formal charge on Oa= 6-(6+2) = 6-(6+1) ? 6-7 = (-)1 for o 2 nu = 6, niab, no? 2 Cone bond). - Formula charge on O. = 6-(6+2) = 6-(6+1) . 3 6.-7. . = 11 for Fa »nv=7, n. 6, no=2 (one bond). a formula charge on Faz 7-(6+2) = 7(6+1) . = 7.7 = 0... for fi > nvat, n=6, no=2 (one bond) 2. Formal charge on Foz 7 (6+2) = 7(6+1) = 7-7. 20. ly over all charge of these compound E = Summation of all formal charges of each atoms - = +1 - | - | +0+ = - 1 . 1 .

Structure to H oa- f-o. for H. nat, n=0, no 2 (one bond). & formal charge on H1-(0+2) = 1-1 for I ³ nuat 0,22 , no= 6 (3. bonds). formal charge on I = 7- (2 + 4) = 7-(2+3). = 7.5 = + 2 . . for Oa a nua 6 A formal charge on ni a4 no= 4 (2 bonds) Oa= 6-(4+4). 26-(4+2) 2.6-6 for a ny = 6; ni= 6, no= ? (1 bond). .:. Formal charge. on Oy = .6 (6+2) 36-(6+1) = 6-7 ?(-)1

for Oe muab, n=6, :No=2 (1 bond) Formal charge on Oc= 6-(6. + 2). 3,6 – 6.6+1). = 6.-7 () Overall charge of this compound. = Seimmation of formal; charges of each atoms..... . 3 Ot 2 + 0 + (-1) +.(-1). = 2-1-1= Oi: Structure-a. L a T structure-b. atom T Formal charge. I .atom formal. charge. el : +1 tila TT00 Ob -1 Coe 1 overall charge = o.) overall charge = -1