Question

The molecular geometry of a molecule describes the three-dimensional shape of just the atoms. This is in contrast to the electronic geometry, which describes the shape of all electron regions.

To determine the molecular geometry of a molecule, one must first determine the electronic geometry by drawing the Lewis structure.

1)Part A
What is the molecular geometry of PH3?
Enter the molecular geometry of the molecule.
2)Part B
What is the molecular geometry of CS2?
Enter the molecular geometry of the molecule.
3)Part C
What is the molecular geometry of H2O?
Enter the molecular geometry of the molecule.

Answer 1

1.)Part A

The molecular geometry of PH3 is trigonal pyramidal. We start with the Lewis structure of PH3. The molecule has eight valence electrons.

2.) Part B

Based on VSEPR Theory (Valence Shell Electron Pair Repulsion Theory) the electron clouds on atoms around the C will repel each other. As a result they will be pushed apart giving the CS2 molecule a linear molecular geometry or shape. The CS2 bond angle will be 180 degrees since it has a linear molecular geometry.

3.) Part 3

Water or H2O has 8 electrons around the central oxygen atom. This means there are four electron pairs arranged in a tetrahedral shape. There are two bonding pairs and two lone pairs. The resulting shape is bent with an H-O-H angle of 104.5°.

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