|
General |
Name, Symbol, Number | Chlorine, Cl, 17 |
Series | Halogens |
Group, Period, Block | 17 (VIIA), 3 , p |
Density, Hardness | 3.214 kg/m3 (273 K), NA |
Appearance | yellowish green |
Atomic Properties |
Atomic weight | amu |
Atomic radius (calc.) | 100 (79) pm |
Covalent radius | 99 pm |
van der Waals radius | 175 pm |
Electron configuration | [Ne]3s2 3p5 |
e-'s per energy level | 2, 8,7 |
Oxidation states (Oxide) | ±1,3,5,7 (strong acid) |
Crystal structure | Orthorhombic |
Physical Properties |
State of matter | gas (nonmagnetic) |
Melting point | 171.6 K (150.7 °F) |
Boiling point | 239.11 K (29.27 °F) |
Molar volume | 17.39 ×10-3 m3/mol |
Heat of vaporization | 10.2 kJ/mol |
Heat of fusion | 3.203 kJ/mol |
Vapor pressure | 1300 Pa |
Speed of sound | no data |
Miscellaneous |
Electronegativity | 3.16 (Pauling scale) |
Specific heat capacity | 480 J/(kg*K) |
Electrical conductivity | no data |
Thermal conductivity | 0.0089 W/(m*K) |
1st ionization potential | 1251.2 kJ/mol |
2nd ionization potential | 2298 kJ/mol |
3rd ionization potential | 3822 kJ/mol |
4th ionization potential | 5158.6 kJ/mol |
5th ionization potential | 6542 kJ/mol |
6th ionization potential | 9362 kJ/mol |
7th ionization potential | 11018 kJ/mol |
8th ionization potential | 33604 kJ/mol |
9th ionization potential | 38600 kJ/mol |
10th ionization potential | 43961 kJ/mol |
Most Stable Isotopes |
|
SI units & STP are used except where noted. |
Chlorine is the
chemical element with
atomic number 17 and symbol Cl. It is a
halogen, found in the
periodic table in
group 17.
Chlorine gas is greenish yellow, is two and one half times as heavy as air, has an intensely disagreeable suffocating odor, and is exceedingly
poisonous.
It is a powerful
oxidizing,
bleaching[?], and disinfecting agent.
As part of
common salt and other compounds, it is abundant in nature and necessary to most forms of life.
The pure chemical element has the physical form of a
diatomic green gas. The name chlorine is derived from
chloros, meaning green, referring to the color of the gas.
This element is a member of the salt-forming halogen series and is extracted from chlorides through oxidation and more commonly, by electrolysis. Chlorine is a greenish-yellow gas that combines readily with nearly all other elements. At 10 °C one liter of water dissolves 3.10 liters of chlorine and at 30 °C only 1.77 liters.
Chlorine is an important chemical in
water purification, in
disinfectants[?] in
bleach and in
mustard gas.
Chlorine is also used widely in the manufacture of many everyday items.
- Used to kill bacteria and other microbes from drinking water supplies. Even small water supplies are now routinely chlorinated.
- Used widely in paper product production, antiseptic, dyestuffs, food, insecticides, paints, petroleum products, plastics, medicines, textiles, solvents, and many other consumer products.
Organic chemistry uses this element extensively as an oxidizing agent and in substitution because chlorine often imparts many desired properties in an organic compound when it is substituted for hydrogen (synthetic rubber[?]).
Others uses are in the production of chlorates, chloroform, carbon tetrachloride, and in the bromine extraction.
Chlorine (
Gr. chloros, greenish yellow) was discovered in
1774 by
Carl Wilhelm Scheele, who mistakenly thought it contained
oxygen. Chlorine was give its name in
1810 by
Humphry Davy, who insisted that it was in fact an element.
Chlorine is manufactured by
electrolysis of an aqueous solution of
sodium chloride.
In nature it is only found combined with other elements chiefly sodium in the form of common salt (NaCl), but also in carnallite[?], and sylvite[?].
Chlorides
Chlorites
Chlorates[?]
Perchlorates[?]
There are two principal stable
isotopes of chlorine, of mass 35 and 37, found in the relative proportions of 3:1 respectively,
giving chlorine
atoms in bulk an apparent atomic weight of 35.5. Chlorine has 9 isotopes with mass numbers ranging from 32 to 40. Only three of these isotopes occur naturally: stable Cl-35 (75.77%)and Cl-37 (24.23%), and
radioactive Cl-36. The ratio of Cl-36 to stable Cl in the environment is about 700 E -15 : 1. Cl-36 is produced in the atmosphere by
spallation[?] of
Ar-36 by interactions with
cosmic ray protons. In the subsurface environment, Cl-36 is generated primarily as a result of
neutron capture[?] by Cl-35 or
muon capture[?] by
Ca-40. Cl-36 decays to
S-36 and to
Ar-36, with a combined
half-life of 308,000 years. The half-life of this
hydrophilic nonreactive isotope makes it suitable for
geologic dating[?] in the range of 60,000 to 1 million years. Additionally, large amounts of Cl-36 were produced by irradiation of
seawater[?] during atmospheric detonations of
nuclear weapons between 1952 and 1958. The residence time of Cl-36 in the atmosphere is about 1 week. Thus, as an event marker of 1950s water in
soil and
ground water[?], Cl-36 is also useful for dating waters less than 50 years before the present. Cl-36 has seen use in other areas of the geological sciences, including dating ice and sediments.
Chlorine irritates respiratory systems especially in children and the elderly.
In its gaseous state it irritates
mucus membranes[?] and when a liquid it burns
skin. It takes as little as 3.5
ppm to be detected as distinct odor but it takes 1000 ppm or more to be fatal. Because of this, chlorine was one ot the gases used during
World War I as a war gas.
Exposure to this gas should therefore not exceed 0.5 ppm (8-hour time-weighted average - 40 hour week.).
Acute exposure to high (but non-lethal) concentrations of Chlorine can result in Pulmonary Edema, or fluid in the lungs, an extremely unpleasant condition. Chronic low-level exposeure weakens the lungs, increasing susceptibility to other lung disorders.
Chlorine gas can be formed when bleach is mixed with urine or with another cleaning product; therefore these combinations should be avoided.
See also: Chlorofluorocarbon