Final answer:
We determine the importance of structures in describing bonding through the evaluation of repulsions in Lewis structures, with the least favorable interactions being found in structures with 90° LP-LP interactions. More favorable is the structure with fewer LP-BP repulsions.
Step-by-step explanation:
To determine which structure is less important in describing the bonding of a molecule, we must consider the Lewis structures and their associated concepts like lone pair (LP) interactions and bond angles. Structure (c) is considered less important because it introduces an LP-LP interaction at a 90° angle, which is energetically unfavorable due to the strong repulsion between lone pairs.
Structure (b), having fewer lone pair-bonding pair (LP-BP) repulsions at 90° compared to the structure (a), is lower in energy, making it more significant in the description of bonding.
Moreover, when considering the best way to represent a molecular structure, one must take into account resonance structures. Resonance structures indicate that a single Lewis structure cannot fully capture the bonding nature within a molecule.
A resonance hybrid is a more accurate representation, describing the overall delocalization of electrons in the molecule. In cases where multiple structures are possible, the structure that best explains the observed properties and behavior is marked as the most contributing.
Therefore, none of the individual structures is 'correct,' and the true structure is a merger—a resonance hybrid of all contributing forms.