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

In terms of reactivity, which metal would be more reactive: Potassium or Aluminium?

1. Potassium

2. Aluminium

3. Both are equally reactive

4. Neither is reactive

The correct answer is: Potassium

Potassium is considered more reactive than aluminium due to its position in the reactivity series of metals. This ranking is based on how readily metals can lose electrons and form positive ions. Potassium is an alkali metal located in group 1 of the periodic table. Alkali metals are known for their high reactivity, particularly with water and oxygen. When potassium reacts, it does so vigorously, often resulting in the release of hydrogen gas and the formation of potassium hydroxide. This high reactivity is mainly because potassium has a single electron in its outermost shell, which it can lose easily to form a stable ion. Aluminium, on the other hand, while it can react with water and acids, does not do so with the same vigor as potassium. Aluminium forms a protective oxide layer on its surface that impedes further reactions in many environments, making it less reactive under standard conditions compared to potassium. Overall, the nature of potassium's electronic configuration and its classification as an alkali metal contributes to its classification as a more reactive metal than aluminium.