Video Transcript
Which shape of a simple molecule is most likely if it contains two bonding pairs and no lone pairs? (A) Trigonal planar, (B) tetrahedral, (C) trigonal bipyramidal, (D) octahedral, or (E) linear.
In this question, we want to identify the three-dimensional shape of a simple molecule that has only two bonding pairs. Determining a molecule’s shape using the number of bonding and lone pairs will initially require memorization. To answer this question, we can draw out the shapes listed and determine which option has only two bonding pairs.
First, a trigonal planar molecule has three bonding pairs or domains around the central atom with no lone pairs. A tetrahedral molecule has four bonding pairs around the central atom and no lone pairs. A molecule that is trigonal bipyramidal has a central atom with three bonding pairs on the same plane and two other bonding pairs rising perpendicular above and below the first plane. A trigonal bipyramidal shape has a total of five bonding pairs and no lone pairs. An octahedral molecule has six bonding pairs all spread 90 degrees apart, while finally a linear molecule has two bonding pairs surrounding the central atom and no lone pairs.
Therefore, the most likely shape of a simple molecule if it contains two bonding pairs and no lone pairs is answer choice (E), linear.
