Question

Select the electron domain geometry and the molecular geometry for an ammonia molecule, NH3. Check all of the boxes that apply. You may use the periodic table if needed.

trigonal-planar electron domain geometry

trigonal-planar molecular geometry

trigonal-pyramidal electron domain geometry

trigonal-pyramidal molecular geometry

tetrahedral electron domain geometry

tetrahedral molecular geometry

Answer 1

- Tetrahedral electron domain geometry (checked)
- Trigonal-pyramidal molecular geometry (checked)

Reason: N in NH3 has 3 bonding pairs + 1 lone pair = 4 electron domains → tetrahedral electron-domain arrangement. With one lone pair, the observed shape of the atoms is trigonal pyramidal (bond angle ≈ 107°).