Lewis Structure Generator
Ammonium ion · NH4+ · Reviewed guide

NH4+ Lewis Structure

Ammonium contains four N–H single bonds, no lone pair on nitrogen and an overall +1 charge. Its molecular geometry is tetrahedral.

Open NH4+ in the generatorSee drawing steps
NH₄⁺
[ H–N⁺(H)(H)–H ]⁺
Four N–H bonds; nitrogen has no lone pair
Valence electrons8
Central atomNitrogen
GeometryTetrahedral
Bond angle109.5°

NH4+ structure overview

Nitrogen contributes 5 electrons and four hydrogens contribute 4, but the positive charge means one electron is removed: 5 + 4 − 1 = 8 electrons. All eight electrons are used in four N–H bonds.

How to draw ammonium

  1. Count 8 electrons.
    Subtract one electron for the +1 charge.
  2. Place nitrogen in the center.
    Hydrogen can only be terminal.
  3. Draw four N–H single bonds.
    The four bonds use all eight electrons.
  4. Do not add a lone pair.
    Unlike NH3, ammonium has no remaining nonbonding pair on nitrogen.
  5. Add brackets and charge.
    Nitrogen has formal charge +1 and the total ion charge is +1.

Formal charge

Nitrogen has 5 valence electrons, no nonbonding electrons and owns half of 8 bonding electrons: 5 − 0 − 4 = +1. Each hydrogen has formal charge 0.

Geometry

Four bonding domains and zero lone pairs around nitrogen produce tetrahedral geometry. The common flat cross drawing is only a 2D Lewis representation.

Common mistakes

  • Using 9 electrons instead of subtracting one for the cation.
  • Leaving the NH3 lone pair on nitrogen.
  • Omitting brackets or the + charge.
  • Calling NH4+ trigonal pyramidal; that geometry belongs to NH3.

Reviewed July 16, 2026. Educational reference only.