Watch the following video to see how metals are good conductors of heat.
Why do metals conduct heat so well? Metals are good thermal conductors because their atoms are closely packed. When you heat the metal the atoms vibrate. The vibrations are passed from one atom to another very rapidly as you will see when you click on the animation below.
Metals also contain large numbers of "free electrons." The electrons drift slowly through the structure as the metal is heated. As the metal heats up the electrons move faster and they travel, colliding with both atoms and other electrons. Thus the heat is passed quickly through the metal.