Conduction in Liquids and Gases

In liquids and Gases, conduction is due to the collisions and diffusion of the molecules during their random motion. As the particles are spaced further apart, there are less frequent collisions in liquids and even lesser in gases. Thus the transfer of kinetic energy from fast moving molecules to neighbouring molecules is slower. This is why most liquids (except for molten mercury) are poor conductors of heat and gases are the poorest (or best insulators) of heat.