Question

why NO2 + and NO2 differ in bond angle?​

Answer 1

Answer:

NO2- has one more electron than NO2, so it has a non-bonding pair ("lone pair") of electrons on nitrogen. This exerts a greater repulsion than the single electron in NO2, so the O-N-O angle is reduced further, to 115.4°. Nitrite ion with an O-N-O bond angle of 115.4° (according to Gillespie and Hargittai).