Question

Use the Molecule Shape simulator to build a molecule. Starting with the central atom, click on the double bond to add one double bond. Then add one single bond and one lone pair. Rotate the molecule to observe the complete geometry. Name the electron group geometry and molecular structure and predict the bond angle.

a) Trigonal Planar; Bent (V-shaped); 120 degrees
b) Linear; Trigonal Planar; 180 degrees
c) Tetrahedral; Trigonal Pyramidal; 109.5 degrees
d) Octahedral; Square Pyramidal; 90 degrees

Answer 1

The electron group geometry for a molecule with one double bond, one single bond, and one lone pair on the central atom is trigonal planar, but the molecular structure is bent or V-shaped with an expected bond angle of less than 120 degrees. The correct option is (a).

Step-by-step explanation:

To build a molecule using the Molecule Shape simulator and add one double bond, one single bond, and one lone pair to the central atom, we determine the shape by considering the number of regions of electron density around the central atom.

With three regions of electron density (one double bond, one single bond, and one lone pair), according to VSEPR theory, we would expect the electron group geometry to be trigonal planar.

However, the molecular structure only takes into account the positions of the nuclei, not the lone pairs.

Therefore, with two bonds and one lone pair, the molecular structure becomes bent or V-shaped, akin to a trigonal planar arrangement with one vertex missing. The presence of the lone pair means the bond angle will be less than 120 degrees due to the lone pair occupying more space.

Consequently, the correct answer is (a) Trigonal Planar; Bent (V-shaped); less than 120 degrees.