Final answer:
When multiple Lewis structures are viable for a molecule, it indicates a resonance situation where the actual bonding is an average of the resonance contributors. Formal charges play a key role in determining the most appropriate structure, favoring adjacent charges that are zero or opposite and negative charges on more electronegative atoms.
Step-by-step explanation:
When a compound has more than one acceptable Lewis structure, these are known as resonance contributors or contributing structures. This resonance situation arises when no single Lewis structure is adequate to represent the actual bonding within a molecule, and the actual structure is an average of these possible structures.
Using the concept of formal charges can help predict the most suitable Lewis structure when multiple structures appear valid. Structures are more favorable when adjacent formal charges are either zero or of opposite signs. Additionally, when choosing among several structures with similar formal charge distributions, preference is given to those with negative formal charges located on the more electronegative atoms.
In essence, the true description of a molecule often lies in a hybrid that shares features from each of the possible resonance structures rather than in a rigid adherence to any one of them.