* Lewis Structure: The central nitrogen atom has three electron domains: one double bond to an oxygen atom, one single bond to another oxygen atom, and one lone pair.
* VSEPR Theory: VSEPR (Valence Shell Electron Pair Repulsion) theory predicts that electron domains around a central atom will arrange themselves to minimize repulsion. Three electron domains result in a trigonal planar electron geometry.
* Molecular Shape: The lone pair on nitrogen exerts a stronger repulsion than the bonding pairs, pushing the two oxygen atoms closer together. This results in a bent or angular molecular shape.
In summary: The NO₂⁻ ion has a bent molecular shape due to the presence of a lone pair on the central nitrogen atom.
