Question

1. this is a diagram of ammonia. this molecule has a central nitrogen atom singly bonded to three hydrogen atoms. the nitrogen atom also has one lone pair of electrons. the shape of this molecule can be classified as ______. a) linear b) trigonal planar c) tetrahedral d) trigonal pyramidal

Explanation:

• Linear: A linear shape occurs when there are 2 bonding pairs and no lone pairs around the central atom (e.g., \(CO_2\)). In \(NH_3\), there are 3 bonding pairs and 1 lone pair, so it is not linear.
• Trigonal planar: A trigonal - planar shape is for a central atom with 3 bonding pairs and no lone pairs (e.g., \(BF_3\)). Since \(NH_3\) has a lone pair, it is not trigonal planar.
• Tetrahedral: A tetrahedral electron - pair geometry occurs when there are 4 electron - pairs (3 bonding + 1 lone pair in \(NH_3\)). But the molecular shape (which ignores lone pairs in its name) is not tetrahedral. The tetrahedral molecular shape is for 4 bonding pairs (e.g., \(CH_4\)).
• Trigonal pyramidal: According to VSEPR (Valence - Shell Electron - Pair Repulsion) theory, for a molecule with the general formula \(AX_3E\) (\(A\) = central atom, \(X\) = bonded atom, \(E\) = lone pair), the molecular shape is trigonal pyramidal. In \(NH_3\), \(N\) is the central atom (\(A\)), 3 \(H\) atoms are bonded (\(X_3\)), and there is 1 lone pair (\(E\)). The lone pair - bond pair repulsions cause the \(NH_3\) molecule to have a trigonal - pyramidal shape.

Answer:

D. trigonal pyramidal