The atmosphere contains three related species—NO₂⁺, NO₂, and NO₂⁻—that differ only in their overall charge and, in the case of NO₂, the presence of an unpaired electron.
(a) For each species (NO₂⁺, NO₂, NO₂⁻), determine the total number of valence electrons that must be shown in a complete Lewis diagram.
(b) Draw the best Lewis structure(s) for each species. Indicate resonance contributors where applicable and clearly mark any unpaired electron.
(c) For each species, assign formal charges to every atom in the structure(s) you drew in part (b).
(d) Using your formal-charge results, rank the three species in order of increasing magnitude of positive charge on the nitrogen atom. Provide a brief justification.
(e) Experimental measurements give N–O bond lengths of 109 pm for NO₂⁺, 120 pm for NO₂, and 126 pm for NO₂⁻. Explain these trends in bond length using your resonance and formal-charge analysis.