Write the resonance structures for SO₃, NO₂ and NO₃⁻.
SO₃ is represented by three canonical forms where the double bond alternates between the sulfur and the three oxygen atoms, connected by a double headed arrow.
NO₂ is represented by two canonical forms where the double bond alternates between the nitrogen and the two oxygen atoms, connected by a double headed arrow.
NO₃⁻ is represented by three canonical forms where the double bond alternates between the nitrogen and the three oxygen atoms, making all N-O bonds equivalent, similar to the CO₃²⁻ ion.
Explanation
According to the concept of resonance, when a single Lewis structure cannot describe a molecule accurately, a number of structures with similar energy, positions of nuclei, bonding and non-bonding pairs of electrons are taken as the canonical structures of the hybrid. These structures are represented by a double headed arrow. For SO₃, NO₂, and NO₃⁻, the double bonds are delocalized over the respective atoms, creating multiple equivalent canonical forms that together form the resonance hybrid.