Question

why are alkali metals more reactive than alkaline - earth metals?

• alkali metals have a single electron in their outermost shell, making losing an electron easier.
• alkali metals have a greater number of protons than alkaline - earth metals.
• alkali metals are denser because of a greater number of neutrons than alkaline - earth metals.
• alkali metals have higher atomic masses than alkaline - earth metals.

Explanation:

To determine why alkali metals are more reactive than alkaline - earth metals, we analyze the electron configuration of these metals. Alkali metals (Group 1) have one valence electron, while alkaline - earth metals (Group 2) have two valence electrons. The reactivity of metals (especially in terms of losing electrons) is related to the ease of losing valence electrons. Since alkali metals have only one electron to lose from their outermost shell, it is easier for them to lose that electron compared to alkaline - earth metals which need to lose two electrons.

• Option 2: "Alkali metals have a single electron in their outermost shell, making losing an electron easier." This option correctly links the number of valence electrons (one for alkali metals) to the ease of losing an electron, which explains their higher reactivity.
• Option 3: The number of protons is related to the element's identity (atomic number) and not directly to reactivity in this context.
• Option 4: The number of neutrons affects the isotope and atomic mass, not reactivity.
• Option 5: Atomic mass is not the reason for the difference in reactivity between alkali and alkaline - earth metals.

Answer:

A. Alkali metals have a single electron in their outermost shell, making losing an electron easier.