The radical species SO can be represented by two nonequivalent Lewis diagrams: I
CHEMISTRY · Single correct · A Level · Chemistry · Bonding · Bonding
Problem
The radical species SO3 can be represented by two nonequivalent Lewis diagrams:
I. The unpaired electron is on sulfur, giving sulfur a formal charge of +1 and one oxygen a formal charge of –1.
II. The unpaired electron is on one oxygen, giving sulfur and all oxygens formal charges of 0.
Which diagram is expected to contribute more to the resonance hybrid, and why?
(a) I, because sulfur, being less electronegative than oxygen, better stabilizes both the positive formal charge and the unpaired electron.
(b) II, because it minimizes the magnitude of formal charges and places the unpaired electron on the more electronegative element.
(c) I, because keeping sulfur at an octet avoids the energetic penalty of an expanded valence shell.
(d) II, because placing the radical on oxygen allows sulfur to form three strong S=O double bonds, increasing stability.