Why metals are good thermal conductors, but polymers are not?

Metals are good thermal conductors because they have close packaged metal ions in their lattice structure but in polymers they have discontinuous structure which make them poor as a conductor.

Explanation: Metals are considered as good thermal conductors because of their lattice structure which has tightly packed ions in it. In the outer shell of atoms the electrons are free to move and thus conduct the electricity but for the polymers, they have a different structure as compared to metals thus it makes it difficult for a polymer to conduct electricity due to high number of discontinuous particle chains. Therefore metals are good conductors , but polymers are not.