Chlorine

Symbol: Cl
Atomic number: 17
Category: halogens
Group: 17
Period: 3
Block: p
Atomic weight: 35.453 g/mol
Electrons per shell: 2, 8, 7
CAS number: 7782-50-5
Phase: gas
Density: 3.2 g/l (0 °C, 101.325 kPa)
Melting point: 171.6 K (-101.5 °C, -150.7 °F)
Boiling point: 239.11 K (-34.4 °C, -29.27 °F)
Crystal structure: orthorhombic
Oxidation states: -1, 1, 3, 5, 7
Electronegativity: 3.16 (Pauling scale)
Name's origin: chloros
Name's meaning: a Greek word which means 'green-yellow' - chlorine has a green-yellow color
Facts:
- is abundant in nature and necessary to most forms of life, including humans
- is part of common salt and other compounds
- is a powerful oxidant and is used in bleaching and disinfectants
- as a common disinfectant, chlorine compounds are us
- in the upper atmosphere, chlorine-containing molecules have been implicated in the destruction of the ozone layer
- is used in making plastics, solvents for dry cleaning and metal degreasing, textiles, agrochemicals, and pharmaceuticals
- is a toxic gas that irritates the respiratory system
- when chlorine is inhaled at concentrations above 30 ppm it begins to react with water and cells which change it into hydrochloric acid (HCl) and hypochlorous acid (HClO)