Question

which molecule exhibits resonance? options: co₂, o₃, becl₂, nf₃

Explanation:

Step1: Recall resonance conditions

Resonance occurs when a molecule has delocalized electrons, often with multiple valid Lewis structures (resonance structures) due to the presence of double bonds and lone pairs in a way that electrons can be delocalized.

Step2: Analyze each molecule

• \( \text{CO}_2 \): Linear structure, \( \text{O}=\text{C}=\text{O} \), but the double bonds are equivalent and there's no delocalization beyond the two double bonds (it has two resonance structures but is often considered with a symmetric structure, but let's check others).
• \( \text{O}_3 \): Ozone has a bent structure. The central O has a double bond with one O and a single bond with another, but due to delocalization, the electrons are spread over the three O atoms. It has resonance structures (e.g., \( \text{O}=\text{O}-\text{O}^- \) and \( \text{O}^- - \text{O}=\text{O} \)).
• \( \text{BeCl}_2 \): Linear, \( \text{Cl}-\text{Be}-\text{Cl} \), no double bonds, so no resonance.
• \( \text{NF}_3 \): Trigonal pyramidal, single bonds (N - F), no double bonds to delocalize, so no resonance.

Answer:

\( \text{O}_3 \) (the molecule in the blue box)