Which statement best explains why alkali metals and halogens react so strongly with other elements?

• A. Alkali metals have very low electronegativity, while halogens have very high electronegativity, making them highly reactive in forming ionic compounds.
• B. Alkali metals and halogens are both noble gases, which makes them highly reactive.
• C. Both alkali metals and halogens have similar electronegativity values, leading to strong covalent bonding.
• D. Their reactivity is due to their large atomic radii and low ionization energies.

Answer: (A)

Verified step by step guidance

1. Understand the properties of alkali metals: They are elements in Group 1 of the periodic table and have a single electron in their outermost shell, which they tend to lose easily due to their low ionization energy and low electronegativity.
2. Understand the properties of halogens: They are elements in Group 17 and have seven electrons in their outermost shell, making them highly electronegative and eager to gain one electron to complete their octet.
3. Recognize that the difference in electronegativity between alkali metals (low) and halogens (high) leads to a strong tendency for alkali metals to lose an electron and halogens to gain an electron, resulting in the formation of ionic bonds.
4. Evaluate the incorrect options: Alkali metals and halogens are not noble gases, so that option is false; they do not have similar electronegativity values, so strong covalent bonding is unlikely; and while atomic radius and ionization energy influence reactivity, the key factor here is the difference in electronegativity driving ionic compound formation.
5. Conclude that the best explanation for their strong reactivity is the large difference in electronegativity, which promotes electron transfer and the formation of stable ionic compounds.