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

Which of the following metals is more reactive than copper?

1. Gold

2. Iron

3. Sodium

4. Silver

The correct answer is: Sodium

Sodium is classified as a highly reactive metal, significantly more reactive than copper. The reactivity of metals is often determined by their ability to lose electrons and form positive ions. In the reactivity series of metals, sodium is positioned higher than copper, indicating that it readily reacts with various substances, including water and acids. This high reactivity is due to sodium's single electron in its outermost shell, which it can easily lose to form a Na⁺ ion. Copper, on the other hand, does not react as vigorously with water or acids. This disparity in reactive behavior helps to explain why sodium is a better candidate for oxidation compared to copper. Other metals like gold, iron, and silver have different reactivity levels; for instance, gold is known for its inertness and resistance to corrosion, while iron is less reactive than sodium but more reactive than copper. Silver, similarly, is less reactive than sodium and does not replace copper in reactions with metal salts. Recognizing these differences is essential for understanding the relative reactivity of these metals.