Why are metals good conductors of electricity?

• A. They have strong ionic bonds.
• B. They are insulators.
• C. They have fully filled valence shells.
• D. They have delocalized electrons that can move freely.

Answer: (D)

Metals conduct electricity well because they form metallic bonds that create a sea of delocalized electrons. In a metal, outer electrons aren’t tied to any single atom; they move freely through the entire lattice. When a voltage is applied, these free electrons drift under the electric field, carrying charge from one side to the other. This high mobility of charge carriers is what makes metals good conductors.

The other ideas don’t fit. Strong ionic bonds imply electrons are locked between ions in an ionic solid, which limits free movement of charge in the solid state. Being an insulator means there aren’t enough mobile charge carriers to support current. Having fully filled valence shells suggests atoms are stable and not inclined to donate electrons for conduction, whereas metals provide a ready pool of mobile electrons that enable conductivity.