Chapter 2, Problem 2.9P

Interpretation Introduction

Interpretation:

Which of the given pair of species will give rise to the strongest intermolecular interactions and the weakest intermolecular interactions is to be determined.

Concept introduction:

There are five types of intermolecular interactions. Ion-ion interactions, dipole-dipole interactions, hydrogen bonding, induced dipole-induced dipole interactions, and ion-dipole interactions. Greater concentration of charge is involved in a stronger intermolecular interaction. Thus, ionic compounds have the strongest intermolecular interactions: ion-ion interactions. This is because ionic compounds have very high concentration of oppositely charged ions. In covalent compounds, polar covalent compounds have stronger intermolecular interactions than similar non-polar compounds. In hydrogen bonding, a hydrogen bond consists of a hydrogen atom donor and a hydrogen atom acceptor. A hydrogen-bond donor is a covalent bond $\text{D-H}$, where D is a highly electronegative atom, such as F, O, or N. A hydrogen-bond acceptor can be any atom with a large concentration of negative charge and a lone pair of electrons. Hydrogen bonding is weaker than ion-ion interactions but usually stronger than dipole-dipole interactions. Induced dipole-induced dipole interactions occur in non-polar covalent compounds, and it is the weakest intermolecular interaction. The order of weakest to strongest intermolecular forces is: induced dipole-induced dipole < Dipole-dipole < Hydrogen bonding < Ion-ion dipole.