Chlorine
Chlorine is named from the Greek chloros, greenish yellow and was discovered in 1774. In nature it is only found in the combined state, chiefly with sodium as common salt, carnallite and sylvite. It is a member of the halogen (salt forming) group of elements and is obtained by the action of oxidizing agents and more often by electrolysis. In its elemental state it is a greenish yellow gas that readily combines directly with nearly all elements. Chlorine is widely used in making many everyday products. It is used for producing safe drinking water throughout the world, and is extensively used in the production of paper products, dyestuffs, textiles, petroleum products, medicines, antiseptics, insecticides, foodstuffs, solvents, paints, plastics and many other consumer products. Chlorine is a respiratory irritant and it was used in world war 1 as a poisonous gas.