Which trend describes halogen reactivity within the group?

Which trend describes halogen reactivity within the group?

• A. Noble gases that are highly reactive.
• B. Very reactive nonmetals; reactivity decreases down the group.
• C. Metals that form alloys.
• D. Inert gases with very low reactivity.

Answer: (B)

Halogens are very reactive nonmetals because they only need one more electron to achieve a stable octet. But their reactivity decreases as you move down the group: fluorine is extremely reactive, while iodine is less reactive. This drop in reactivity is due to increasing atomic size and more shielding from inner electrons, which weakens the nucleus’s pull on the outer electrons and makes it harder for the atom to attract another electron. So the statement that describes halogen reactivity within the group is that they are very reactive nonmetals, with reactivity decreasing down the group. The other descriptions—noble gases that are highly reactive, metals that form alloys, and inert gases with very low reactivity—do not fit halogens.

Halogens are very reactive nonmetals because they only need one more electron to achieve a stable octet. But their reactivity decreases as you move down the group: fluorine is extremely reactive, while iodine is less reactive. This drop in reactivity is due to increasing atomic size and more shielding from inner electrons, which weakens the nucleus’s pull on the outer electrons and makes it harder for the atom to attract another electron. So the statement that describes halogen reactivity within the group is that they are very reactive nonmetals, with reactivity decreasing down the group. The other descriptions—noble gases that are highly reactive, metals that form alloys, and inert gases with very low reactivity—do not fit halogens.