Chlorine much like other Halogens has antiseptic properties. It is used in swimming pools commonly and also making drinking water safe by killing bacteria. It is also used in the production of many plastics such as PVC and also the production of insecticides and solvents. Chlorine was first produced by Carl Wilhelm Scheele in 1774 when he reacted Manganese dioxide with hydrochloric acid, at the time he did not know the name of these chemicals and instead named them as the alchemical forms of pyrolusite and spiritus salis. It took many years before Humphrey Davy concluded that the new gas discovered was a new element, he named it Chlorine after the Greek ‘Chloros’ meaning yellow green. It is located in Group 17 as a non metal yellow gas with a pungent smell familiar with swimming pools at room temperature. It has a melting point of -155°c and a boiling point of -100°c. Chlorine gas has been used in the production of many solvents but it was not until 1915 during World War 1 that the german army used chlorine gas as a chemical weapon.
Carl Wilhelm Scheele
Used in water purification, bleaches, acids and many, many other compounds such as chlorofluorocarbons (CFC).
Salt (sodium chloride, NaCl) is its most common compound. Commercial quantities are produced by electrolysis of aqueous sodium chloride (seawater or brine from salt mines).