Halogens — Definition, Formula, Properties & Uses | AllChemicals | AllChemicals

What is Halogens?

Halogens are the elements of Group 17 (VIIA) of the periodic table: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). They are highly reactive nonmetals characterized by having seven valence electrons, a strong tendency to gain one electron to form halide ions (X⁻), and the ability to form diatomic molecules (F₂, Cl₂, Br₂, I₂). Halogens are widely used as disinfectants, in the synthesis of polymers and pharmaceuticals, and in industrial chemical processes.

Key Facts

Term Halogens

Index All "H" terms

Frequently Asked Questions

What is Halogens?

Halogens are the elements of Group 17 (VIIA) of the periodic table: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). They are highly reactive nonmetals characterized by having seven valence electrons, a strong tendency to gain one electron to form halide ions (X⁻), and the ability to form diatomic molecules (F₂, Cl₂, Br₂, I₂). Halogens are widely used as disinfectants, in the synthesis of polymers and pharmaceuticals, and in industrial chemical processes.

More "H" Terms

Haber Process N₂ + 3H₂ ⇌ 2NH₃ | ΔH = −92 kJ/mol Hafnium Hf Half Cell Half Life Half-Cell E = E° − (RT/nF)lnQ Half-Life A(t) = A₀e^(−λt); t½ = ln2/λ Half-Reaction Halide X⁻ (e.g., F⁻, Cl⁻, Br⁻, I⁻) Halogen F₂, Cl₂, Br₂, I₂, At; Group 17; ns²np⁵ valence configuration Halogenation C-X + Cl₂/Br₂ (hv or AlCl₃) → C-X(halogen); EAS or radical pathway Hard Acid Hard acid: small, highly charged, low polarisability (e.g., H⁺, Mg²⁺, Al³⁺) Hard Base Hard base: high EN, low polarisability (e.g., F⁻, OH⁻, NH₃, H₂O)

View all "H" terms →