Halogengassen

Halogengassen, or halogen gases, are the gaseous forms of the halogen elements when they occur as elemental diatomic molecules. The halogens are fluorine (F), chlorine (Cl), bromine (Br), iodine (I) and astatine (At). Under standard conditions, fluorine and chlorine are gases, bromine is a liquid, and iodine is a solid; astatine is radioactive and extremely scarce, with properties that are not well established.

As a group, halogen gases are highly reactive and highly electronegative. They form compounds with most metals and many nonmetals and are strong oxidizers. They are typically toxic and corrosive, producing fumes that can irritate the eyes, skin, and respiratory tract. Physically, fluorine gas is a pale yellow, chlorine gas a greenish-yellow, bromine is a red-brown liquid at room temperature, and iodine forms a violet solid. At standard conditions, these elements do not all exist as gases; only F2 and Cl2 do.

In chemistry and industry, halogen gases play specialized roles. Chlorine gas is widely used for water disinfection, sanitation, and in chemical synthesis. Fluorine gas is employed in the manufacture of many organofluorine compounds and in etching and semiconductor processes, though its handling is extremely hazardous. Bromine and iodine are less volatile as gases under ordinary conditions but can be used in various syntheses and as reagents. Astatine, being radioactive and scarce, has limited practical applications.

Production of halogen gases varies by element. Chlorine is primarily produced by the electrolysis of sodium chloride solutions (the chlor-alkali process). Fluorine is generated industrially through specialized electrochemical methods involving fluorides and hydrogen fluoride, conducted under stringent safety controls. Safety and containment are critical when handling halogen gases due to their reactivity and toxicity.