Which element is classified as an alkali metal? Rb Sr Zr Cl
The Correct Answer and Explanation is:
The correct answer is Rb (Rubidium).
Explanation:
Alkali metals are the elements found in Group 1 of the periodic table. This group is known for having a single electron in their outermost shell, making them highly reactive, especially with water. The alkali metals include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). These metals are characterized by their softness, low melting points, and the ability to form strong bases (alkalies) when combined with water.
Here’s a breakdown of the options given:
- Rb (Rubidium): This is an alkali metal. Rubidium is found in Group 1, and like all alkali metals, it has one electron in its outermost shell, making it highly reactive, especially with water. Its reactivity increases as you move down the group, so rubidium reacts more violently than sodium but less than cesium.
- Sr (Strontium): This is an alkaline earth metal, which is found in Group 2 of the periodic table. Alkaline earth metals have two electrons in their outer shell and are not as reactive as alkali metals, but they are still reactive with water.
- Zr (Zirconium): This is a transition metal, found in Group 4. Transition metals have a wide range of properties but are not part of the alkali or alkaline earth metals.
- Cl (Chlorine): This is a halogen, found in Group 17. Halogens are highly reactive nonmetals, and like alkali metals, they readily form salts when combined with metals, but they are not classified as alkali metals.
Thus, rubidium is the only element in the list that qualifies as an alkali metal.
