Name       : Chlorine
Symbol     : Cl
Atomic #   : 17
Atom weight: 35.453
Melting P. : -100.98
Boiling P. : -34
Oxidation  : -1
Pronounced : KLOR-een OR KLOR-in
From       : Greek chloros, "greenish yellow"
Identified : Carl Wilhelm Scheele in 1774
Appearance : Greenish-yellow, disagreeable gas
Note       : Deadly; the most common weapons in gas warfare of World War I 

[Properties]

  Chlorine is a memeber of the Group-VIIA, or halogen, elements. Notice that
the names of all the halogens end with -ine: fluorine (F), bromine (Br),
iodine (I), and astatine (At).
  Being a halogen means that chlorine is a very reactive ion, forming -1
bonds with nearly all metals. For example, the best known compound of
chlorine, sodium chloride (NaCl), combines the chlorine ion with the 
metallic element, sodium. Like the other halogens, elemental chlorine forms
a diatomic moleucle, or halide.
  Chlorine is a nonmetal that exists as a greenish-yellow, highly corrosive
gas at room temperature. It is essential that you avoid inhaling even the
smallest does of concentrated chlorine gas. If you want to get some
appreciation of its suffocating odor, you can experience it at safe
concentrations around large swimming pools and in areas where someone is
using chlorine bleach.