Only fluorine among the nonmetals is more chemically active. Chlorine belongs to the halogen family of elements, found in group VIIa of the periodic table . Chlorine water has strong oxidizing properties resulting from the oxygen set free when the unstable hypochlorous acid decomposes.
Chlorine reacts readily with hydrogen to form hydrogen chloride.
In the presence of moisture it combines directly with certain metals, such as copper and iron, to form chlorides . Iron ignites when heated in a chlorine atmosphere. Because of its activity chlorine does not occur uncombined in nature, but its compounds are numerous and abundant. Chlorine is produced commercially chiefly by the electrolysis of sodium chloride, either molten or in solution. Other chlorides are sometimes employed.