CHEM 121 glossary

Polarizability

How easily a molecule's or atom's electron cloud is distorted to form a temporary dipole. It increases with the number of electrons and the size of the cloud, and higher polarizability means stronger dispersion forces.

Noble-gas boiling points rise as the atoms get bigger and more polarizable.

Example

At room temperature $\ce{F2}$ and $\ce{Cl2}$ are gases, $\ce{Br2}$ is a liquid and $\ce{I2}$ is a solid: the larger the halogen, the more polarizable its electron cloud.