Conduction in Liquids and Gases

The particles in liquids and gases are spaced further apart than those in solids. Therefore, collisions between molecules are less frequent, thus the process of conduction in liquids and gases is inefficient.

This also explains why air is a poor conductor of heat as compared to water, which in turn is a poor conductor of heat compared to most solids.
Most liquids are poor conductors of heat except molten mercury.

Conduction in Solids--way1

When one end of an object is supplied with thermal energy, the molecules gain kinetic energy and vibrate vigorously. As they vibrate faster, they will collide with neighbouring particles making them vibrate too. Due to the transfer of kinetic energy, the less energetic molecules would vibrate faster and collide with other less energetic molecules in the other end.
This continues until heat energy from the hottert part spreads throughout the colder part.

Energy is passed on from one molecule to another without the molecule moving out from their fixed position. Conduction also happens in all matter, as long as there is a medium.

As conduction transfers thermal energy by the vibration of particles, the closer the particles are packed togther, the more quickly it is for the energy to pass from one particle to another via vibration. That is the reason why conduction occurs the fastest in solids, as compared to liquids and gases.

Conduction in Solids--way2

Transferring of thermal energy from hot end to cold end by molecular vibration is quite slow. Another much faster mechanism of thermal energy transfer is, free electrons diffusion. Solids can either be metals or non-metals. Solids which are metal have free electrons which are not possessed by non-metals. When thermal energy is supplied, besides the transfer of heat energy through vibrating molecules, these free electrons also gain kinetic energy. These fast moving electrons then diffuse / spread into the cold end of the metal. They collide with the atoms in the cooler parts of the metal and transfer their kinetic energies to them.

A good conductor is a kind of material with more free electrons, because thermal energy can be transferred more quickly. All metals are therefore good conductor.

The rate of heat transfer determines whether an object is a good/ poor conductor.

Conduction

Conduction

Definition: The process of thermal energy transfer without any flow of the material medium.
Without any flow of the material medium=Without the medium moving
Heat is transmitted through a medium from its hotter part to its colder part until they are both at the same temperature.
Conduction happens in all matter as long as there is a medium.
The 3 main medium are solids, liquids and gases. Transfer of heat energy is fastest in solids, and slowest in gases.