Chapter 9.1, Problem 4CP

Interpretation Introduction

Interpretation:

The approximate value of the indicated bond angle is to be determined.

Concept introduction:

To determine the geometry, first draw a Lewis structure of the molecule.

Count the number of electron pairs or domains around the central atom. Electron domain is the bond, and lone pair of electrons are placed around the central atom.

Electron domains are the bond and lone pair of electrons around the central atom.

According to VSEPR, the electron domains repel each other, and arrange themselves as far apart as possible in space.

Molecular geometry is the spatial arrangement of bonded atoms. If no lone pairs are present, then molecular geometry is identical to the electron domain geometry.

The repulsion factor working between lone pair and lone pair is greater as compared to the lone pair–bond pair repulsion, which is further greater than the bond pair–bond pair repulsion.

To draw a Lewis structure, first, the sum of the valence electrons of all the atoms is determined. In case of a polyatomic ion, electrons are added if there is negative charge, and subtracted if there is a positive charge on the ion.

A skeleton structure is drawn connecting all the atoms and each bond contains two electrons.

Then, the electrons are placed on the terminal atoms as lone pairs, to complete their octet.

Remaining electrons are placed on central atom as lone pairs.

If there are no valence electrons to complete the octet of the central atom, then one or more terminal atoms share a lone pair to form a double bond.