Halogens form Group 17 and are highly reactive p-block elements. They readily form salts and covalent compounds and are central to water treatment, polymers, pharmaceuticals, electronics and specialty chemical manufacturing.
Overview
Elemental halogens and many halogen compounds can be corrosive, toxic or environmentally significant, so containment and materials compatibility are critical. Astatine and tennessine are radioactive; their relevance is almost entirely scientific.
Elements in this category
Using periodic-table categories in engineering
Periodic-table categories are useful for organizing trends, but they are not a substitute for material specifications. Engineering performance depends on purity, microstructure, processing history, temperature, environment and the way an element is combined into alloys or compounds.
Explore further: Periodic Table · Materials Library · Material Properties

