How many equivalent resonance structures can be drawn for the molecule of SO₃without having to violate the octet rule on the sulfur atom? A) 5 B) 1 C) 2 D) 4 E) 3

Question

Quizplus · Accepted Answer

The sulfur atom in the molecule has 6 valence electrons. To satisfy the octet rule, it needs two more electrons. There are three possibilities to add those electrons: through a single bond, through a double bond, or through a lone pair.
1. Single bond: S=O-S-S. In this structure, all atoms satisfy the octet rule, but the sulfur atom has a formal charge of +1.
2. Double bond: S=S-O-S. In this structure, the sulfur atoms satisfy the octet rule, but the oxygen has a formal charge of -1.
3. Lone pair: :S=O-S:S. In this structure, the sulfur atoms satisfy the octet rule, and there are no formal charges.
4. Combination of #1 and #2: :S=O-S=S
5. Combination of #1 and #3: S=O-S:S

Therefore, there are a total of three equivalent resonance structures without violating the octet rule on the sulfur atom.

How Many Equivalent Resonance Structures Can Be Drawn for the Molecule