Which characteristic describes halogens?

Which characteristic describes halogens?

• A. Low electronegativity and low electron affinity; readily lose electrons
• B. High electronegativity and electron affinity; readily gain an electron; highly reactive with metals; one valence electron away from full octet.
• C. Dense metals
• D. Non-reactive gases

Answer: (B)

Halogens are highly electronegative nonmetals that sit one electron short of a full octet. They have seven valence electrons, so they readily gain one electron to complete the octet and reach the electron configuration of the nearest noble gas. This tendency is driven by their high electron affinity and strong ability to attract electrons, so energy is released when they gain that electron. Because of this, halogens are very reactive with metals, typically forming halide ions with a −1 charge and giving rise to ionic salts when paired with metal cations. This combination of high electronegativity, high electron affinity, a drive to gain one electron, and reactivity with metals best captures what halogens are. Contrast that with descriptions of low electronegativity and low electron affinity and losing electrons—those describe metals rather than halogens. And describing halogens as dense metals or as non-reactive gases doesn’t fit their nonmetal nature and their well-known reactivity.

Halogens are highly electronegative nonmetals that sit one electron short of a full octet. They have seven valence electrons, so they readily gain one electron to complete the octet and reach the electron configuration of the nearest noble gas. This tendency is driven by their high electron affinity and strong ability to attract electrons, so energy is released when they gain that electron. Because of this, halogens are very reactive with metals, typically forming halide ions with a −1 charge and giving rise to ionic salts when paired with metal cations. This combination of high electronegativity, high electron affinity, a drive to gain one electron, and reactivity with metals best captures what halogens are.

Contrast that with descriptions of low electronegativity and low electron affinity and losing electrons—those describe metals rather than halogens. And describing halogens as dense metals or as non-reactive gases doesn’t fit their nonmetal nature and their well-known reactivity.