Here's why:

* Transition elements are located in groups 3-12 of the periodic table.

* Copper (Cu) is located in group 11, making it a transition element.

The transition elements are characterized by:

* Having partially filled d-orbitals in their atoms or ions.

* Often forming colored compounds.

* Exhibiting variable oxidation states.

* Being good conductors of heat and electricity.

Copper fits all these characteristics.