To determine which element is more reactive than rubidium (Rb), we need to understand some key concepts in chemistry, specifically about the periodic table and the reactivity of elements.
1. Identify Rubidium's Group:
Rubidium (Rb) is located in Group 1 of the periodic table. Group 1 elements are known as alkali metals and are highly reactive. The reactivity of alkali metals increases as you move down the group.
2. Compare the Options:
- Aluminum (Al):
Aluminum is found in Group 13 of the periodic table. While aluminum is reactive, it is not in Group 1, so we can conclude it is not more reactive than rubidium.
- Cesium (Cs):
Cesium is found below rubidium in Group 1 of the periodic table. As previously mentioned, the reactivity of alkali metals increases as you move down the group. Therefore, cesium (Cs) is more reactive than rubidium (Rb).
- Strontium (Sr):
Strontium is located in Group 2 of the periodic table. Group 2 elements, known as alkaline earth metals, are less reactive than Group 1 alkali metals. Thus, strontium is not more reactive than rubidium.
- Beryllium (Be):
Beryllium is also found in Group 2 of the periodic table. It is less reactive compared to alkali metals in Group 1, and therefore, it is not more reactive than rubidium.
3. Conclusion:
Among the given options, cesium (Cs), which is in Group 1 and below rubidium, will be the most reactive element.
Therefore, the correct answer is:
B. Cesium (Cs)
