Question

Explain the term "polarizability." What kind of molecules tend to have high polarizabilities? What is the relationship between polarizability and intermolecular forces?

Short answer

Polarizability refers to the ability of a molecule to have its electron cloud distorted by an external electric field, forming a temporary dipole. Molecules with larger, more diffused electron clouds tend to have high polarizability. A direct relationship exists between polarizability and intermolecular forces such as dispersion forces, with higher polarizability leading to stronger forces.

Step-by-step solution

Defining Polarizability

Polarizability is the ability or tendency of a molecule (atom or ion) to be distorted by an external electric field. It involves the stretching or altering of the electron cloud, causing the molecule to establish a temporary dipole.

Molecules with High Polarizability

Molecules that tend to have high polarizabilities are those with large, more diffused electron clouds. This is often seen in atoms with a large number of electrons, such as larger molecules, or elements further down a group in the periodic table. The size and shape of the electron cloud play significant roles in polarizability.

Relationship between Polarizability and Intermolecular Forces

There is a direct and significant relationship between polarizability and the strength of intermolecular forces, particularly London dispersion forces. The larger the polarizability of a molecule, the stronger are its dispersion forces. This is because when an atom's or a molecule's electron cloud is more easily distorted (i.e., it has high polarizability), it can induce a dipole in its neighbor more effectively, leading to stronger intermolecular forces.