Why are gasses Poor conductors of heat?

Gasses are poor conductors of heat because their particles are widely spread apart which means collisions do not happen frequently. Collisions of particles are required to generate heat.

Explanation:

Gases are poor conductors of heat as for conduction to take place the particles have to be touching in order to pass the energy on. This is why conduction through solids and liquids take place. However since gasses are spread out and have a gasses have a lower density. This means that gasses are poor conductors as the partials do not touch to transfer the heat and that the collisions to transfer energy are infrequent, unless in certain conditions.

Some practical uses for gasses as poor  conductors are in double glazed windows, as the air acts as an insulator.