The most stable Lewis structure for the nitrate ion (NO3–) involves a central nitrogen atom surrounded by three oxygen atoms. Nitrogen forms double bonds with two of the oxygen atoms and a single bond with the third oxygen atom. The single-bonded oxygen carries a negative charge. This structure is stabilized by resonance, meaning the double bonds can be delocalized among the three oxygen atoms.
The molecular geometry of NO3– is trigonal planar. This means the three oxygen atoms are arranged symmetrically around the central nitrogen atom, with bond angles of approximately 120 degrees.
Due to its symmetrical shape and the equal distribution of electron density, the nitrate ion is nonpolar. The charges are evenly distributed, resulting in no net dipole moment.