Which of the following best explains what resonance structures are?

• A. Different molecules with the same molecular formula but different connectivity of atoms.
• B. Different Lewis structures for the same molecule that differ only in the placement of electrons, not the arrangement of atoms.
• C. Structures that show the actual movement of atoms during a chemical reaction.
• D. Isomers that have the same connectivity but differ in the arrangement of atoms in space.

Answer: (B)

Verified step by step guidance

1. Understand that resonance structures are a way to represent a single molecule using multiple Lewis structures.
2. Recognize that these Lewis structures differ only in the placement of electrons (such as pi electrons or lone pairs), not in the positions of the atoms themselves.
3. Note that resonance structures do not represent different molecules or isomers; instead, they are different depictions of the same molecule's electron distribution.
4. Realize that resonance helps to describe the delocalization of electrons within a molecule, which cannot be accurately shown by a single Lewis structure.
5. Conclude that the best explanation for resonance structures is: 'Different Lewis structures for the same molecule that differ only in the placement of electrons, not the arrangement of atoms.'