Question

Account for the following:

NO₂ readily forms a dimer whereas ClO₂ does not.

Give appropriate reason for the following observation:

NO₂ readily forms a dimer, whereas ClO₂ does not.

Answer 1

1. NO₂ readily forms a dimer (N₂O₄) because it has an unpaired electron that pairs up by dimerisation, increasing stability.
2. ClO₂ also has an unpaired electron but does not form a dimer because the \[\ce{Cl - O}\] bonding and structure do not favour pairing due to its geometry and electron distribution.
3. In NO₂, dimer formation reduces the overall energy by pairing radicals, while in ClO₂, steric and electronic factors prevent stable dimer formation.