Textbook 6A.15

[Sophia Schiro]

Draw the Lewis structure or symbol of each reactant, identify the Lewis acid and the Lewis base, and then draw the Lewis structure of the product (a complex) for the following Lewis acid–base reactions: Cl- + SO2

Can anyone explain why the lewis structure for the answer has a lone pair on the S and a single bond from S-O, rather than having just a double bond between S and O?

[Praveena Ratnavel - 1A]

This is because based on formal charges, the oxygen would rather carry the negative than the sulfur because the oxygen is more electronegative.

[Kiku Shirakata 2A]

Hello,

One way of thinking about this is by first counting the number of valence electrons: S + O*2 = 6 + 6*2 = 18
Thus, we need to count 18 electrons after drawing the Lewis structure. If we had a double bond between both S and O bonds, the total number of the electron would be 16 instead of 18. Thus, we need to make one of the bonds a single bond and add a lone pair to the S to make the total count 18 electrons.

Hope this helps!