Like in chapter 5 I change the order of the topics, to give a more logical development of the ideas. In chapter 5 I first gave the rigorous development and then explained how some simple models fit in. The book mixes these two ideas. In this chaper we will do the same. Metals are very important,as we all know.
Metals are good conductors for electricity and heat, they are ductile and malleable.
They can be shaped easily for any application we want. It turns out that the thermal conductivity has the same temperature behavior as discussed in the previous chapter, but that the values are much higher in metals. In order to understand all of this we have to discuss the electrons in metals. The first approach to this was by Drude around 1900. He treated the conduction electrons as a gas of independent particles that can exchange energy and momentum via collisions, exactly as we did for phonons in the previous chapter.