Which property would you expect for a material with a three-dimensional covalent network and no free electrons?

• A. High electrical conductivity
• B. Poor electrical conductivity
• C. Conducts only when molten
• D. Conducts in solid state and gas state

Answer: (B)

Electrical conductivity comes from charge carriers that can move. In a three-dimensional covalent network, atoms are held together by strong covalent bonds in a rigid lattice, and the electrons are largely involved in those bonds rather than roaming freely. Without mobile charge carriers, electric current can’t flow easily, so the material acts as a poor conductor. That’s why the expected property is poor electrical conductivity.

In contrast, high conductivity would require free electrons or ions, and a material like this wouldn’t suddenly become conductive just because it’s melted, since there aren’t free ions to move. It also wouldn’t conduct in solid and gas states.