Which of the following is not a member of the halogen family?

Radon is not a member of the halogen family. The halogens are a group of chemical elements found in Group 17 of the periodic table, and they include fluorine, chlorine, bromine, iodine, and astatine. These elements are characterized by their reactivity and tendency to form salts with metals. Chlorine, bromine, and astatine are all classified as halogens, with chlorine being a commonly recognized gas at room temperature, bromine existing as a liquid, and astatine being a rare radioactive element.

In contrast, radon is classified as a noble gas, which is found in Group 18 of the periodic table. Noble gases are characterized by their lack of reactivity due to having a complete valence electron shell, which distinguishes them from the more reactive halogens. Radon is also heavier and has unique properties related to its radioactivity and stability, further separating it from the characteristics of halogens.