Chlorine is a chemical element that exists as a diatomic molecule, Cl2. Under normal temperature and pressure, it is a highly toxic, suffocating gas with a distinct yellow-green color and a strong, pungent odor. Its density is greater than that of air. The melting point is -101.00°C, and the boiling point is -34°C. Chlorine is soluble in water and alkaline solutions, readily dissolves in organic solvents (such as carbon tetrachloride), but has low solubility in saturated brine. It is easily compressed and can be liquefied into a yellow-green, oily liquid known as liquid chlorine. Chlorine is widely used in disinfection and sterilization, industrial production, chemical manufacturing, water treatment, and synthesis of materials.