Textbook Question
(a) An AB6 molecule has no lone pairs of electrons on the A atom. What is its molecular geometry? (c) For the AB4 molecule in part (b), predict the molecular geometry.
12. Molecular Shapes & Valence Bond Theory
Molecular Geometry
Multiple Choice
Which of the following molecules has a linear shape?
A
NO2+
B
SO2
C
NO2-
D
O3
Verified step by step guidance1
To determine the molecular shape, we need to use the VSEPR (Valence Shell Electron Pair Repulsion) theory, which predicts the geometry of molecules based on the repulsion between electron pairs around a central atom.
First, let's consider the molecule NO2+. Count the total number of valence electrons: Nitrogen (N) has 5 valence electrons, and each Oxygen (O) has 6 valence electrons. Since there is a positive charge, subtract one electron. This gives us a total of 5 + 6 + 6 - 1 = 16 valence electrons.
Next, arrange the electrons to form bonds and lone pairs around the central atom (Nitrogen in this case). NO2+ has a linear shape because it has two bonding pairs and no lone pairs on the central atom, resulting in a bond angle of 180 degrees.
Now, consider SO2. Count the valence electrons: Sulfur (S) has 6 valence electrons, and each Oxygen (O) has 6 valence electrons. This gives us a total of 6 + 6 + 6 = 18 valence electrons. SO2 has a bent shape due to the presence of lone pairs on the central atom.
Finally, analyze NO2- and O3. NO2- has a bent shape due to the presence of lone pairs, and O3 also has a bent shape due to resonance and lone pairs. Therefore, the only molecule with a linear shape is NO2+.
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