Charged species require an adjusted electron count and bracket notation. Polyatomic ions have internal covalent bonds, while simple ionic compounds are usually represented as separate ions rather than one shared-electron molecular structure.
For NO3−, add one electron to the neutral atom total. For NH4+, subtract one. This adjustment is made once for the entire species, not once per atom.
Nitrogen contributes 5, four hydrogens contribute 4 and the +1 charge removes one, leaving 8 electrons. Four N–H bonds use all 8. Nitrogen has no lone pair, the ion is tetrahedral and the bracketed structure carries +1 overall.
Open NH4+ in the generator →Nitrate has 24 valence electrons. Its major contributors contain one N=O bond and two N–O single bonds. The double bond can occupy any of the three N–O positions, so the measured bonds are equivalent in the resonance hybrid.
Open NO3− in the generator →A formula such as NaCl describes an extended ionic solid, not a discrete Na–Cl molecule with one ordinary covalent bond. A basic Lewis representation shows electron transfer and separate ions:
For compounds such as CaCl2, show Ca2+ and two separate Cl− ions. Do not imply that the solid consists of isolated triatomic molecules.
In ammonium nitrate, NH4NO3, draw the covalent Lewis structure of NH4+ and the resonance structures of NO3− separately, then show the electrostatic pairing of the two charged ions. The covalent bonds remain inside each polyatomic ion.
Local key formatting varies. Compact formulas such as NH4+ and NO3- are the best starting point.
Last reviewed: July 15, 2026.