Why does copper conduct electricity so well?

Copper is an exceptionally effective electrical conductor primarily due to the behavior of its electrons and the nature of its atomic structure.

Like other metals, copper is held together by metallic bonds, in which valence electrons are not bound to individual atoms but instead float freely between metal ions. These non-localized, or "free," electrons are able to move easily through the crystal lattice when an electrical force is applied, creating an electric current.12

The high conductivity of copper is specifically attributed to the high mobility of these free electrons. While conductivity depends on both the number of available electrons and their ability to move through the solid, copper’s structure allows for minimal interference with electron flow. Furthermore, copper’s conductivity is highly sensitive to purity; impurities or alloying elements introduce defects into the crystal structure that scatter electrons and increase electrical resistance, which is why pure copper is a superior conductor compared to copper alloys.231