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

How can the structure of metals be described?

1. A random arrangement of atoms

2. A giant regular structure of positive ions surrounded by delocalised electrons

3. A lattice of only metal ions

4. A network of non-metallic elements

The correct answer is: A giant regular structure of positive ions surrounded by delocalised electrons

The structure of metals can be best described as a giant regular structure of positive ions surrounded by delocalised electrons. In metallic bonding, metal atoms tend to lose some of their electrons, which become delocalised. This means that the electrons are not bound to any specific atom and can move freely throughout the structure. The positive metal ions form a closely-packed lattice arrangement, which contributes to the metal's properties such as malleability, ductility, and conductivity. The delocalised electrons act as a glue that holds the positively charged ions together, allowing the metal to maintain its structure while also enabling the movement of electrons. This delocalisation is crucial for the conductivity of metals, as these electrons can easily carry electric current. The other options do not accurately describe the metallic structure. A random arrangement of atoms does not reflect the order and regularity found in metallic lattices. A lattice of only metal ions overlooks the significant presence of delocalised electrons that are essential for bonding in metals. Finally, a network of non-metallic elements does not pertain to metallic structures, as metals are characterized by their unique electron configuration and bonding arrangements that differ from those of non-metals.