Halogens are the elements fluorine, chlorine, bromine, iodine, astatine; these form group seven (VIIA) of the periodic table. They are all non-metals and strongly electronegative.

Some generalistic trends among the halogens. As you go down the group -

• There's an extra shell of electrons for every row you go down.
• They're less reactive because of this.
• They're darker in colour.
• There are state changes as you go down - Fluorine and Chlorine are gases, Bromine is a liquid and Iodine is a solid.
• They have a higher melting point and a higher boiling point.

Halogens are all non-metals with coloured vapours. Halogens are poisonous. They all form molecules which are pairs of atoms, and will form both ionic and covalent bonds.

Hal"o*gen (?), n. [Gr. "a`ls, "alo`s, salt + -gen: cf. F. halogene.] Chem.

An electro-negative element or radical, which, by combination with a metal, forms a haloid salt; especially, chlorine, bromine, and iodine; sometimes, also, fluorine and cyanogen. See Chlorine family, under Chlorine.

 

© Webster 1913.