How do London dispersion forces increase?

Question

Delilah Anderson · Accepted Answer

Factors that affects the strength of a dispersion force include : #"Distance between molecules, polarizability and the shape of the molecule."#

Factors influencing a dispersion force's strength

• "Distance between molecules." To be effective, these attractive forces need to exist very close between molecules.

• "Polarizability": larger molecules have more electrons and are therefore more polarizable, which results in stronger London dispersion forces. It is the ease with which an electron cloud can be deformed.

• "Shape of the molecule." The 3-dimensional shape of the molecule influences the surface area available for interaction with neighboring molecules; the greater the surface area, the greater the dispersion forces. The boiling points of spherical and more cylindrically shaped molecules are indicative of smaller London dispersion forces between them (e.g. pentane b.p 309.4 K and neopentane b.p 282.7.4 K).

Elias Aguila · Answer

undefined London dispersion forces increase with increasing molecular size and surface area, as well as with increasing polarizability of the molecules involved. These forces are the weakest type of intermolecular forces and arise due to temporary fluctuations in electron distribution within molecules, leading to temporary dipoles. Larger molecules with more electrons and greater surface area exhibit stronger London dispersion forces because they have a greater potential for inducing temporary dipoles in neighboring molecules. Similarly, molecules with higher polarizability, meaning they can easily have their electron clouds distorted, also experience stronger London dispersion forces.