What is the impact of metallic bonding on thermal conductivity?

Metallic bonding significantly enhances thermal conductivity due to the free movement of electrons.

In more detail, metallic bonding is a type of chemical bonding that arises from the electrostatic attractive force between conduction electrons and positively charged metal ions. It is the main type of bonding that occurs in metals and it gives metals their unique properties, one of which is high thermal conductivity.

Thermal conductivity is the property of a material to conduct heat. In metals, this is particularly high because of the presence of free electrons. In a metal lattice, atoms are arranged in a regular pattern and the outer shell of electrons is delocalised, meaning they are free to move throughout the entire structure. These free electrons are also known as conduction electrons.

When heat is applied to a metal, the atoms in the metal vibrate more. These vibrations are passed on to the nearby free electrons, which then move and collide with other electrons and atoms, transferring the kinetic energy and hence the heat. This process is very efficient in metals due to the high density of free electrons, leading to a high rate of collision and therefore a high rate of heat transfer. This is why metals are good conductors of heat.

In contrast, in non-metals, there are no free electrons to carry the heat energy, so they generally have lower thermal conductivity. The heat energy is transferred by vibrations of the atoms or molecules, but this process is less efficient than in metals.

In summary, the presence of metallic bonding, with its characteristic free electrons, significantly enhances the thermal conductivity of metals. This is a key property that makes metals useful in many applications where heat transfer is important, such as in cooking utensils, radiators and electronic devices.