Final answer:
In certain cases, there can be more than one Lewis structure for a molecule, which is known as resonance. When determining the most appropriate Lewis structure for a molecule with resonance, structures with all formal charges of zero are preferred, and if nonzero formal charges are necessary, structures with the smallest nonzero charges are favored. It is also important to consider the placement of formal charges on more electronegative atoms and the arrangement of adjacent formal charges.
Step-by-step explanation:
There can be more than one Lewis structure for a molecule in certain cases, and this is known as resonance. Resonance occurs when there are multiple equivalent ways to arrange the electrons in a molecule or ion. One example of resonance is the ozone (O3) molecule, which can be represented by two different Lewis structures. In these cases, the actual structure of the molecule is considered to be a combination or hybrid of the different resonance structures.
When determining the most appropriate Lewis structure for a molecule with resonance, there are certain guidelines we can follow. First, structures with all formal charges equal to zero are preferred. If nonzero formal charges are necessary, structures with the smallest nonzero formal charges are favored. Additionally, it is preferable for adjacent formal charges to be zero or of opposite signs. Finally, negative formal charges should be placed on more electronegative atoms when there are multiple valid structures.