What would you expect about diamond's electrical conductivity?

• A. Conducts electricity
• B. Does not conduct
• C. Conducts when molten or dissolved
• D. Conducts in gas phase

Answer: (B)

Electrical conductivity depends on having mobile charge carriers that can move under an electric field. In diamond, each carbon atom is held in a rigid covalent network, forming strong bonds with four neighbors in a tetrahedral arrangement. All electrons are involved in these bonds, so there are no free electrons or ions left to carry charge as the material conducts. That’s why pure diamond acts as an electrical insulator in solid form. The idea that materials conduct when molten or dissolved applies to ionic compounds, where ions become mobile, but diamond doesn’t form mobile ions when heated. In the gas phase under normal conditions, there are very few charge carriers as well, so it doesn’t conduct electricity either. So the expected behavior is that diamond does not conduct electricity.