Which concept describes multiple Lewis structures that are distinct but equivalent and obey the octet rule?

• A. Formal charges
• B. Resonance Structures
• C. Hybrid orbitals
• D. Octet rule variations

Answer: (B)

Resonance structures capture the idea that a molecule can be drawn more than one valid Lewis form, with the same connectivity of atoms but different placements of electrons (especially the pi bonds and lone pairs). When these alternative forms are distinct yet equivalent and each atom satisfies the octet, they describe the same molecule as resonance forms. The real structure is a resonance hybrid, reflecting delocalized electrons that give bond orders between single and double. A classic example is benzene, where two Kekulé forms differ by where the double bonds sit, yet every carbon completes its octet and there are no net charges in either form. The actual molecule isn’t flipping between forms; it’s a blended state with electrons spread over the ring, which explains its equal bond lengths and intermediate bond character. Other ideas mentioned—formal charges, hybrid orbitals, or variations of the octet rule—describe different concepts, not the situation of multiple equivalent Lewis structures sharing electrons through delocalization.