Halogenien

Halogenien is a term that refers to members of Group 17 of the periodic table, also known as the halogens. This group consists of five elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). These elements are highly reactive nonmetals and share several common properties.

One of the most notable characteristics of halogens is their diatomic molecular form in their elemental state, meaning they exist as pairs of atoms, such as F2, Cl2, Br2, and I2. Astatine is an exception, and its molecular form is less well-defined due to its rarity and radioactivity. Halogens are typically colored, with fluorine being a pale yellow gas, chlorine a greenish-yellow gas, bromine a reddish-brown liquid, and iodine a violet solid. Their reactivity decreases down the group, with fluorine being the most electronegative and reactive element.

Halogens readily form salts when they react with metals, which is the origin of their name, derived from the Greek words "hals" (salt) and "gennan" (to form). They also form a wide range of compounds with other elements, including hydrogen halides (such as HCl, hydrochloric acid) and interhalogen compounds. These compounds have diverse applications, including disinfectants (chlorine, bromine), refrigerants (chlorofluorocarbons, though many are now phased out), and as components in pharmaceuticals and plastics. Due to their reactivity, elemental halogens are rarely found free in nature and are usually obtained from their mineral compounds.