The nitrate ion NO3- has three resonance structures. In each resonance structure, the nitrogen atom is at the center, and the three oxygen atoms are bonded to it. The nitrogen atom has a positive charge, and one of the oxygen atoms has a negative charge. The pi electron density is distributed across the atoms as follows:Resonance Structure 1:N +1 is double-bonded to O1, and single-bonded to O2 and O3. O1 has no formal charge, while O2 and O3 have a formal charge of -1. The pi electrons are distributed in the double bond between N and O1.Resonance Structure 2:N +1 is double-bonded to O2, and single-bonded to O1 and O3. O2 has no formal charge, while O1 and O3 have a formal charge of -1. The pi electrons are distributed in the double bond between N and O2.Resonance Structure 3:N +1 is double-bonded to O3, and single-bonded to O1 and O2. O3 has no formal charge, while O1 and O2 have a formal charge of -1. The pi electrons are distributed in the double bond between N and O3.In reality, the nitrate ion is a hybrid of these three resonance structures, with the pi electron density delocalized across all three oxygen atoms. This delocalization results in equivalent N-O bond lengths and strengths, making the nitrate ion more stable.