Question

Sodium and sodium iodide can both conduct electricity when molten, but only sodium can conduct electricity when solid. Explain this difference in conductivity in terms of the structures of sodium and sodium iodide.

A) Sodium forms a metallic lattice, while sodium iodide forms a covalent lattice.
B) Sodium has more free electrons than sodium iodide.
C) Sodium has a higher density than sodium iodide.
D) Can't be determined

Answer 1

The difference in conductivity between solid sodium and solid sodium iodide is due to their lattice structures. Sodium forms a metallic lattice, allowing the free movement of electrons and conductivity in both solid and molten states. Sodium iodide, on the other hand, forms a covalent lattice in the solid state, preventing the movement of ions and resulting in no conductivity. When molten, the covalent bonds break, allowing the ions to move freely and conduct electricity.

Step-by-step explanation:

The difference in conductivity between sodium and sodium iodide is due to the structures of the two compounds. Sodium forms a metallic lattice, which means that its atoms are arranged in a regular pattern with a sea of delocalized electrons that can move freely. This allows for the conduction of electricity in both solid and molten states of sodium. On the other hand, sodium iodide forms a covalent lattice, with individual sodium and iodide ions held together by covalent bonds. In the solid state, these ions are fixed in their positions and cannot move, resulting in no conductivity. However, when sodium iodide is molten, the covalent bonds are broken and the ions can move freely, allowing for the conduction of electricity.