Chlorine liquefied under pressure, sealed in a quartz ampoule and then in an acrylic cube. Chlorine, a chemical element belonging to the halogen group, is most commonly found in the compound sodium chloride. It is a strong oxidizing agent, which led it to its bleaching and disinfectant uses, as well as uses as an essential reagent in the chemical industry. Elemental chlorine is extremely dangerous and poisonous for all lifeforms, but chloride ions are necessary to most forms of life.Photo: Alchemist-hp