International General Certificate of Secondary Education (IGCSE) Chemistry Practice Exam

Which structure allows metals to conduct heat well?

1. A simple molecular structure

2. A giant ionic structure

3. A metallic lattice structure with delocalised electrons

4. A covalent network structure

The correct answer is: A metallic lattice structure with delocalised electrons

Metals are known for their excellent conductivity of heat and electricity, which can largely be attributed to their unique metallic lattice structure. In this structure, metal atoms are arranged in a regular pattern, and the outer electrons from these atoms are delocalized, meaning they are not bound to any specific atom but are free to move throughout the lattice. The presence of these delocalized electrons is crucial because they can carry thermal energy rapidly throughout the metal. As heat is applied to one part of the metallic structure, the delocalized electrons gain energy, move faster, and can transfer this energy quickly to other parts of the metal. This efficient transfer of energy is what makes metals good conductors of heat. In contrast, structures such as simple molecular arrangements, giant ionic lattices, or covalent network structures do not have this mechanism of delocalized electrons, which significantly reduces their ability to conduct heat compared to metals. Instead, these structures rely on localized electron bonds, which do not facilitate the same level of energy transfer as seen in metallic lattices.