Final answer:
The three criteria for choosing the best resonance structure are minimizing formal charges, maximizing the octet rule, and considering electronegativity.
Step-by-step explanation:
When choosing the best resonance structure, there are three criteria to consider:
- Minimize formal charges: A resonance structure with lower or no formal charges is more stable than one with higher charges. For example, in the carbonate ion (CO3^2-), the structure with two double bonds and no formal charges is more stable than the structure with one double bond and two negative charges.
- Maximize octet rule: Resonance structures that satisfy the octet rule for all atoms are more stable. However, some atoms, like boron and hydrogen, can have incomplete octets in certain resonance structures.
- Electronegativity: The less electronegative an atom donating a lone pair of electrons for the resonance, the stronger the resonance. This means that resonance involving less electronegative atoms is generally more favorable.