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:

To determine the molecular shape of ammonia (\(NH_3\)):

1. First, identify the electron - domain geometry. The central nitrogen atom has 3 bonding domains (from the three \(N - H\) bonds) and 1 non - bonding domain (the lone pair of electrons). The total number of electron domains is \(3 + 1=4\).
2. For a molecule with 4 electron domains, the electron - domain geometry is tetrahedral. But when considering the molecular shape (the arrangement of the atoms), we ignore the lone pair. The three hydrogen atoms are arranged around the nitrogen atom in a way that forms a trigonal pyramidal shape.

• A linear shape (option A) has a bond angle of \(180^{\circ}\) and 2 bonding domains. Ammonia has 3 bonding domains and 1 lone pair, so it's not linear.
• A trigonal planar shape (option B) has 3 bonding domains and no lone pairs on the central atom, with a bond angle of \(120^{\circ}\). Ammonia has a lone pair, so it's not trigonal planar.
• A tetrahedral shape (option C) is the electron - domain geometry when there are 4 electron domains (3 bonding and 1 non - bonding). But the molecular shape (the shape of the atoms) is not tetrahedral because of the lone pair. The molecular shape, which considers only the atoms, is trigonal pyramidal.
• The trigonal pyramidal shape (option D) occurs when there are 3 bonding domains and 1 non - bonding (lone pair) domain on the central atom. This matches the structure of ammonia, where the nitrogen has 3 \(N - H\) bonds and 1 lone pair.

Answer:

D) trigonal pyramidal