Which lattice conducts electricity in the solid state?

• A. Ionic lattice
• B. Simple covalent lattice
• C. Macro covalent lattice
• D. Metallic lattice

Answer: (D)

Conductivity in a solid hinges on having mobile charge carriers. In a metallic lattice, valence electrons are not bound to any single atom; they form a delocalized sea that moves freely through the lattice when a potential difference is applied. This drift of electrons carries electric current, so the solid conducts. The metal ions stay fixed in place within the lattice, bonded by metallic bonds, while the electrons provide the flow. In contrast, an ionic lattice fixes its ions in place in the solid, so there are no free charges to move; a solid ionic crystal typically conducts only when melted or dissolved. In a simple covalent lattice, electrons are localized within strong covalent bonds and cannot move freely, leading to poor conductivity. The same idea carries to large covalent networks, where electrons are tied up in bonds as well. Thus, the metallic lattice is the one that conducts electricity in the solid state.