What element is classified as an alkali metal? A. Rb B. Sr C. Zr D. Cl
The Correct Answer and Explanation is:
The correct answer is A. Rb (Rubidium).
Explanation:
Alkali metals are a group of elements found in Group 1 of the periodic table. These metals are characterized by having a single electron in their outermost shell, making them highly reactive, especially with water. They are all soft, low-melting metals that are highly conductive of heat and electricity. Alkali metals tend to form ions with a +1 charge by losing their single outer electron.
Let’s break down the options:
- Rb (Rubidium): Rubidium is an alkali metal. It is found in Group 1 of the periodic table, and like all alkali metals, it has one electron in its outer shell. Rubidium is highly reactive and typically found in compounds rather than in its pure form.
- Sr (Strontium): Strontium is an alkaline earth metal, not an alkali metal. It is found in Group 2 of the periodic table and has two electrons in its outermost shell. While it shares some similarities with alkali metals, its chemical properties are different.
- Zr (Zirconium): Zirconium is a transition metal and is found in Group 4. Transition metals have different properties compared to alkali metals, including higher melting points and lower reactivity with water.
- Cl (Chlorine): Chlorine is a halogen, not an alkali metal. It is located in Group 17 of the periodic table and has seven electrons in its outer shell. Halogens are highly reactive nonmetals, particularly with metals like sodium or potassium, but they are not classified as alkali metals.
In conclusion, rubidium (Rb) is the correct answer because it is the only alkali metal among the listed elements.
