The molecular geometry of the nitrate ion (NO3–) is trigonal planar.
This shape arises because the nitrogen atom is at the center, bonded to three oxygen atoms. In the nitrate ion, nitrogen has a positive oxidation state, and it shares its electrons with three oxygens. The ideal bond angles in a trigonal planar structure are approximately 120 degrees.
The presence of a lone pair of electrons is crucial in determining the shape of the molecule. However, in NO3–, there are no lone pairs on the nitrogen atom, which reinforces the trigonal planar geometry. Each N-O bond in this ion has a partial double bond character due to resonance, but the overall arrangement remains trigonal planar.