Name chlorine
Symbol Cl
Atomic Weight 35.453
Atomic Number 17
CAS ID 7782-50-5
Group Number 17
Group Name Halogen
Period Number 3
Origin of Name Greek, chloros = "pale green."
Year Discovered 1774
Discovery Credits C. W. Scheele at Uppsala, Sweden.
Class Non-Metallic
Color Yellowish green
Standard State Gas at 77 F & 298 K
Description Yellow-green, dense, sharp smelling gas, Cl2; produced on a large scale by electrolysis of sodium chloride. Used as bleaching agent and to make organochlorine solvents and polymers (PVC).

Diagnostic tests: 
Chlorine salts (along with F, Br, and I) will give a blue color to flames when heated on a copper disk.
Treatment of the salt with concentrated H2SO4 acid will effervesce with the evolution of a greenish, sharp smelling gas (Cl2). Chlorine sometimes found associated with bromine or iodine so a precipitate with AgNO3 solution is white (AgCl), cream (AgBr), or yellow (AgI) depending on which anion predominates. The precipitate is soluble in NH4OH

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