A conductor is normally made of atoms with ____ electrons in the valence shell.

• A. 0
• B. 1, 2, or 3
• C. 4
• D. 5

Answer: (B)

Electrical conduction relies on electrons that can move freely through the material. In metals, the outer electrons aren’t tightly bound to any one atom; they form a delocalized sea that can drift under an electric field. Atoms with 1, 2, or 3 electrons in their valence shell readily contribute to this mobile population, so metals with these valence counts conduct well. When the valence shell is more filled, electrons are more tightly bound in bonds and are less free to move, making the material less conductive. An atom with zero valence electrons wouldn’t provide outer electrons to participate in conduction, so it wouldn’t form a good conductor. That’s why the description “1, 2, or 3 valence electrons” best matches typical conductors.