Conduction by free electron diffusion
Conduction by free electron diffusion is the transfer of thermal energy through a metal by the movement of free electrons.
Metals have many free electrons (electrons which are not bound to an atom). When a part of the metal is heated, some electrons gain energy. These electrons travel at high speeds around the metal.
The free electrons collide with stationary atoms in other parts of the metal and transfer some of their energy.
In this way thermal energy is transferred across the metal. This is a very fast process.
When cooking with a saucepan that has a metal handle you will notice the handle gets hot quite quickly.
If the handle is made from wood or plastic it takes a lot longer for the handle to heat up.