What is the shape of an NH3 molecule?A.LinearB.Trigonal-planarC.Trigonal-pyramidalD.BentSUBMITarrow_backPREVIOUS

Breakdown the Problem

1. Understand the molecular geometry of ammonia (NH₃).
2. Identify the number of bonding pairs and lone pairs on the central atom (nitrogen).

Relevant Concepts

1. VSEPR Theory: Valence Shell Electron Pair Repulsion (VSEPR) theory helps predict the shape of molecules based on the repulsion between electron pairs.
2. Lewis Structure: Drawing the Lewis structure of ammonia can help visualize bonding and lone pairs.

Analysis and Detail

1. Lewis Structure:

   • Nitrogen (N) has 5 valence electrons.
   • Each hydrogen (H) contributes 1 valence electron.
   • NH₃ has a total of $5 + 3 \times 1 = 8$ valence electrons.
   • The structure will show one nitrogen atom at the center with three hydrogen atoms bonded to it.
   • There is one lone pair of electrons on the nitrogen atom.

2. Determining Molecular Shape:

   • The nitrogen atom has four regions of electron density (three N-H bonds and one lone pair).
   • According to VSEPR theory, four regions of electron density create a tetrahedral electron geometry.
   • However, the presence of the lone pair (which takes up more space) changes the molecular geometry to trigonal pyramidal.

Verify and Summarize

Based on the analysis:

• The molecular shape of NH₃ is determined to be trigonal pyramidal due to the presence of three bonding pairs and one lone pair.

Final Answer

The shape of an NH₃ molecule is C. Trigonal-pyramidal.