The nitrite ion (NO2–) can be analyzed using Lewis theory to understand the arrangement of electrons around its central atom. The central atom in the nitrite ion is nitrogen (N). To draw the Lewis structure, we start by calculating the total number of valence electrons available for the ion. Nitrogen has 5 valence electrons, and each oxygen atom contributes 6, totaling 12 from oxygen. We also account for the negative charge of the ion, which adds an additional electron, bringing the total to 13 valence electrons.
Next, we place nitrogen in the center and arrange the two oxygen atoms around it. We connect one oxygen atom with a double bond (consuming 4 electrons) and the other oxygen atom with a single bond (consuming 2 electrons), which accounts for a total of 6 electrons used. This leaves us with 7 remaining electrons. We place 3 lone pairs on the singly bonded oxygen atom and 1 lone pair on the nitrogen atom.
The resultant structure shows that the central nitrogen atom is surrounded by two bonding pairs (one with each oxygen) and one unshared pair of electrons. This configuration corresponds to the first option: a) two bonding and one unshared pair of electrons. Therefore, the correct answer is option A.