Nitrogen dioxide, NO2, is a bent, paramagnetic molecule that can be represented by two equivalent Lewis resonance contributors.
A chemist measures the N–O bond length in gaseous NO2 to be 119pm. For comparison, an isolated N–O single bond is typically 136pm, whereas an N=O double bond is about 115pm.
(a) Draw the complete Lewis structure for each of the two major resonance contributors of NO2 and assign formal charges to every atom.
(b) Using the resonance hybrid concept, explain why the two N–O bonds in NO2 are experimentally identical in length.
(c) Rationalize the measured bond length of 119pm in the context of the data for typical N–O single and double bonds.
(d) Predict qualitatively how the N–O bond length would change (increase, decrease, or stay the same) if NO2 were converted to the cation NO2+, and justify your prediction with reference to resonance and formal charge considerations.