Chapter 11, Problem 11.126QP

Interpretation Introduction

Interpretation:

Gecko’s toes stick easily to a wall. But their toes lift off a surface as easily. This is has to be explained.

Concept introduction:

                Intermolecular forces are Van der Waals forces.  They are weak and have three types viz., London dispersion forces, dipole-dipole forces and hydrogen bonding. Hydrogen bonding is relatively the strongest one.

• Intermolecular forces are the forces acting between molecules whereas Intramolecular forces are the forces that operate within a molecule.
• Hydrogen bonding is a special type of Dipole-dipole forces but stronger than the former.
• London dispersion forces exist in non-polar covalent compounds whereas dipole-dipole forces exist in polar covalent compounds but both are weak.
• Larger the molecular size, stronger the London dispersion force.
• Arrangement of major types of intermolecular forces in increasing order of strength:

$\text{London}\text{dispersion}\text{forces}\text{<}\text{Dipole-dipole}\text{forces}\text{<}\text{Hydrogen}\text{bonding}$

There exist no deviations in this arrangement.