The nitrate ion NO3- has three resonance structures. In each resonance structure, the central nitrogen atom is bonded to three oxygen atoms. The nitrogen atom has a positive charge, and one of the oxygen atoms has a negative charge. The other two oxygen atoms have double bonds with the nitrogen atom. The three resonance structures differ in the position of the negatively charged oxygen atom and the double bonds.Resonance structure 1:O=N-O - -OResonance structure 2:O - -N=O-OResonance structure 3:O-O - -N=OThese three resonance structures contribute equally to the overall structure of the nitrate ion, which is best represented as a hybrid of these three structures. The actual structure of the nitrate ion has equivalent bond lengths and bond strengths between the nitrogen and oxygen atoms, which is not accurately represented by any single resonance structure.