Chlorine

General

Name	Chlorine	Symbol	Cl
Atomic number	17	Atomic weight	35.453
Density @ 293 K	0.003214 g/cm3	Atomic volume	22.7 cm3/mol
Group	Halogen	Discovered	1774

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States

State (s, l, g)	g
Melting point	172.22 K	Boiling point	239.2 K
Heat of fusion	3.203 kJ/mol	Heat of vaporization	10.20 kJ/mol

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Energies

1st ionization energy	1251.1 kJ/mole	Electronegativity	3.16
2nd ionization energy	2297.3 kJ/mole	Electron affinity	349 kJ/mole
3rd ionization energy	3821.8 kJ/mole	Specific heat	0.48 J/gK
Heat atomization	121 kJ/mole atoms

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Oxidation & Electrons

Shells	2,8,7	Electron configuration	[Ne] 3s2 3p5
Minimum oxidation number	-1	Maximum oxidation number	7
Minimum common oxidation number	-1	Maximum common oxidation number	7

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Appearance & Characteristics

Structure	layers of Cl2	Color	greenish-yellow
Uses	bleach (NaOCl), PVC pipe	Toxicity	yes
Hardness	mohs	Characteristics	diatomic(Cl2), corrosive

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Reactions

Reaction with air	none	Reaction with 6M HCl	mild, =>HOCl, Cl-
Reaction with 6M HCl	mild, =>HOCl, Cl-	Reaction with 15M HNO3	mild, =>HClOx, NOxCl, NOx
Reaction with 6M NaOH	mild, =>OCl-, Cl-

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Other Forms

Number of isotopes		2	Hydride(s)		HCl
Oxide(s)		Cl2O ClO2 Cl2O7	Chloride(s)		Cl2

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Radius

Ionic radius (2- ion)	pm	Ionic radius (1- ion)	167 pm
Atomic radius	100 pm	Ionic radius (1+ ion)	pm
Ionic radius (2+ ion)	pm	Ionic radius (3+ ion)	pm

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Conductivity

Thermal conductivity		0.01 J/m-sec-deg	Electrical conductivity		0 1/mohm-cm
Polarizability		2.2 A^3

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Source	Halite, brine (misc)	Rel. abund. solar system	3.719 log
Abundance earth's crust	2.1 log	Cost, pure	0.15 $/100g
Cost, bulk	$/100g

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History:

(Gr. chloros, greenish yellow) Discovered in 1774 by Scheele, who thought it contained oxygen; named in 1810 by Davy, who insisted it was an element. In nature it is found in the combined state only, chiefly with sodium as common salt (NaCl), carnallite, and sylvite. It is a member of the halogen (salt-forming) group of elements and is obtained from chlorides by the action of oxidizing agents and more often by electrolysis; it is a greenish-yellow gas, combining directly with nearly all elements. At 10C one volume of water dissolves 3.10 volumes of chlorine, at 30C only 1.77 volumes. Chlorine is widely used in making many everyday products. It is used for producing safe drinking water the world over. Even the smallest water supplies are now usually chlorinated. It is also extensively used in the production of paper products, dyestuffs, textiles, pretoleum products, medicines, antiseptics, insecticides, foodstuffs, solvents, paints, plastics, and many other consumer products. Most of the chlorine produced is used in the manufacture of chlorinated compounds for sanitation, pulp bleaching, disinfectants, and textile processing. Gurther use is in the manufacture of chlorates, chloroform, carbon tetrachloride, and in the extraction of bromine. Organic chemistry demands much from chlorine, both as an oxidizing agent and in substitution, since it often brings many desired properties in an organic compound when substituted for hydrogen, as in one form of synthetic rubber. Chlorine is a respiratory irritant. The gas irritates the mucous membranes and the liquid burns the skin. As little as 3.5 ppm can be detected as an odor, and 1000 ppm is likely to be fatal after a few deep breaths. It was used as a war gas in 1915. Exposure to chlorine should not exceed 0.5 ppm (8-hour time-weighted average - 40 hour week.)

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