The ammonia molecule (NH_3) in the diagram has the observed bond orientation because:

• A. all four electron pairs around nitrogen are equally shared, resulting in a tetrahedral geometry
• B. the nitrogen atom forms double bonds with each hydrogen, causing a linear geometry
• C. the hydrogen atoms are arranged in a planar triangle due to resonance
• D. the lone pair on nitrogen repels the bonding pairs, resulting in a trigonal pyramidal geometry

Answer: (D)

Verified step by step guidance

1. Identify the central atom in the ammonia molecule, which is nitrogen (N), and note that it has three hydrogen atoms bonded to it.
2. Determine the total number of electron pairs around the nitrogen atom, including both bonding pairs (shared with hydrogen atoms) and lone pairs (non-bonding pairs).
3. Recall that nitrogen has five valence electrons; three are used to form bonds with hydrogen atoms, and the remaining two electrons form one lone pair.
4. Understand that electron pairs repel each other and arrange themselves to minimize repulsion, which leads to a specific molecular geometry according to VSEPR (Valence Shell Electron Pair Repulsion) theory.
5. Recognize that the lone pair on nitrogen exerts a stronger repulsive force than bonding pairs, pushing the hydrogen atoms downward and resulting in a trigonal pyramidal molecular geometry rather than a tetrahedral or planar shape.