Chlorine (Cl)
halogenGas
Standard Atomic Weight
35.45 u [35.446, 35.457]Electron configuration
[Ne] 3s2 3p5Melting point
-101.5 °CBoiling point
-34.04 °CDensity
3.214 kg/m³Oxidation states
−1, +1, +2, +3, +4, +5, +6, +7Electronegativity (Pauling)
3.16Ionization energy (1st)
12.967633 eVDiscovery year
1774Atomic radius
100 pmDetails
Chlorine is a reactive halogen and a yellow-green diatomic gas, Cl₂, under ordinary conditions. It is a strong oxidizing agent and occurs naturally mainly as chloride salts, especially in seawater and evaporite minerals. Chlorine chemistry is central to water disinfection, inorganic chlorides, chlorinated solvents, polymers, and many industrial oxidation and substitution processes. The element has two stable isotopes, ³⁵Cl and ³⁷Cl.
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 10°C one volume of water dissolves 3.10 volumes of chlorine, at 30°C only 1.77 volumes.
The name derives from the Greek chloros for "pale green" or "greenish yellow" colour of the element. It was discovered by the Swedish pharmacist and chemist Carl-Wilhelm Scheele in 1774. In 1810, the English chemist Humphry Davy proved it was an element.
Since it combines directly with nearly every element, chlorine is never found free in nature. Chlorine was first produced by Carl Wilhelm Scheele, a Swedish chemist, when he combined the mineral pyrolusite (MnO2) with hydrochloric acid (HCl) in 1774. Although Scheele thought the gas produced in his experiment contained oxygen, Sir Humphry Davy proved in 1810 that it was actually a distinct element. Today, most chlorine is produced through the electrolysis of aqueous sodium chloride (NaCl).
From the Greek word chloro, greenish yellow. Discovered in 1774 by Scheele, who thought it contained oxygen. Chlorine was named in 1810 by Davy, who insisted it was an element.
Pure chlorine is a dense yellow-green gas with a sharp, irritating odor. It condenses to an amber liquid under pressure or cooling and freezes to a pale solid. The gas is visibly colored even at moderate concentrations in laboratory vessels.
Elemental chlorine, Cl₂, is used chiefly as a chemical intermediate rather than as an end product. Major uses include production of vinyl chloride for polyvinyl chloride, manufacture of chlorinated solvents and intermediates, bleaching of some pulp and textile streams, and synthesis of inorganic chlorides. Chlorine and hypochlorite solutions are widely used for drinking-water, wastewater, and swimming-pool disinfection. Hydrochloric acid, HCl, made directly or as a by-product, is also an important industrial reagent.
Chlorine is commonly used as an antiseptic and is used to make drinking water safe and to treat swimming pools. Large amounts of chlorine are used in many industrial processes, such as in the production of paper products, plastics, dyes, textiles, medicines, antiseptics, insecticides, solvents and paints.
Two of the most familiar chlorine compounds are sodium chloride (NaCl) and hydrogen chloride (HCl). Sodium chloride, commonly known as table salt, is used to season food and in some industrial processes. Hydrogen chloride, when mixed with water (H2O), forms hydrochloric acid, a strong and commercially important acid. Other chlorine compounds include: chloroform (CHCl3), carbon tetrachloride (CCl4), potassium chloride (KCl), lithium chloride (LiCl), magnesium chloride (MgCl2) and chlorine dioxide (ClO2).
Chlorine is a very dangerous material. Liquid chlorine burns the skin and gaseous chlorine irritates the mucus membranes. Concentrations of the gas as low as 3.5 parts per million can be detected by smell while concentrations of 1000 parts per million can be fatal after a few deep breaths.
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, petroleum products, medicines, antiseptics, insecticides, food, 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. Further 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.
Isotopes in Earth/Planetary Science
Because molecules, atoms, and ions of the stable isotopes of chlorine possess slightly different physical and chemical properties, they commonly will be fractionated during physical, chemical, and biological processes, giving rise to variations in isotopic abundances and in atomic weights. There are substantial variations in the isotopic abundances of chlorine in natural terrestrial materials (Fig. IUPAC.17.1). These variations are useful for investigating the origin of substances and studying environmental, hydrological, and geological processes. Chlorine is subject to isotopic fractionation by physical and chemical processes. Variations in isotopic compositions of stable chlorine isotopes provide evidence for ultrafiltration and crystallization of brines and indicate sources of chlorine-bearing contaminants, such as solvents and rocket fuels, in the environment [151] H. G. M. Eggenkamp, R. Kreulen, A. F. Koster Van Groos. Geochim. Cosmochim. Acta59, 5169 (1995)., [152] M. A. Stewart, A. J. Spivack. Rev. Mineral. Geochem.55, 231 (2004)..
Isotopes in Forensic Science and Anthropology
Analyses of chlorine isotopes and other environmental tracers can help to identify whether an environmental contaminant is of anthropogenic origin or naturally occurring. For example, perchlorate (ClO4 -) can be of anthropogenic origin and is also found naturally. Perchlorate is a widespread groundwater contaminant that can interfere with hormone production in the thyroid gland by displacing iodide. Both the stable chlorine isotope-amount ratio n(37Cl)/n(35Cl) and the mole fraction of 36Cl, n(36Cl)/n(Cl), can provide useful information about origins of perchlorate in the environment (Fig. IUPAC.17.2). Such information may be important for legal reasons and for remediation of contaminated areas [152] M. A. Stewart, A. J. Spivack. Rev. Mineral. Geochem.55, 231 (2004)., [153] J. K. Böhlke, N. C. Sturchio, B. Gu, J. Horita, G. M. Brown, W. A. Jackson, J. R. Batista, P. B. Hatzinger. Anal. Chem.77, 7838 (2005)..
Isotopes in Geochronology
Radioactive 36Cl provides a useful tool to determine ages in geology and hydrology. Some radioactive 36Cl is cosmogenic and enters the terrestrial environment in precipitation. Because of its long half-life of 3.01×105 years, the level of 36Cl in aquifers can be measured and used to estimate ages (on the order of 105 to 106 years) of old meteoric groundwater (water that was originally precipitation) [155] F. M. Phillips. “Chlorine-36”, in Environmental Tracers in Subsurface Hydrology, P. G. Cook and A. L. Herczeg (Eds.), Kluwer Academic Publishers, Boston MA (2000)..
Thermonuclear bomb tests in the ocean produced large amounts of 36Cl by neutron reactions with 35Cl in seawater. This was especially prevalent in the late 1950s. Large amounts of this anthropogenic 36Cl were distributed throughout the atmosphere, deposited with precipitation, and incorporated into terrestrial soils and groundwater. This enriched 36Cl has been used as a tracer of meteoric water from that era [156] F. M. Phillips, J. L. Mattick, T. A. Duval, D. Elmore, P. W. Kubik. Water Resour. Res.24, 877 (1988)..
Chlorine commonly forms chloride compounds in the −1 oxidation state, including sodium chloride, NaCl, hydrogen chloride, HCl, and many metal chlorides. It also forms positive oxidation states in oxyanions such as hypochlorite, ClO⁻, chlorite, ClO₂⁻, chlorate, ClO₃⁻, and perchlorate, ClO₄⁻. Important molecular compounds include chlorine dioxide, ClO₂, and phosphorus trichloride, PCl₃. Organic chlorides range from simple chloromethane, CH₃Cl, to complex polymers and pharmaceuticals.
See more information at the Chlorine compound page.
Chlorine, Cl₂, is acutely toxic by inhalation and strongly irritating to eyes, skin, and the respiratory tract. It reacts with moisture in tissues to form acidic and oxidizing species. Concentrated hypochlorite solutions and chlorine dioxide, ClO₂, are hazardous oxidizers, and mixing hypochlorite with acids can release chlorine gas. Many chloride salts are low-hazard at ordinary exposure levels, but toxicity depends strongly on the accompanying cation or organic group.
Chlorine is a respiratory irritant. The gas irritates the mucus 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. In fact, chlorine was used as a war gas in 1915.
Chlorine is abundant in the environment mainly as chloride, Cl⁻, dissolved in seawater, brines, soils, and biological fluids. Marine aerosols, evaporite deposits, volcanic gases, and weathering move chlorine through natural cycles. Reactive chlorine compounds are formed naturally in the atmosphere and by organisms, but industrial organochlorines have added persistent pollutants in some settings. Chloride is mobile in water and is not readily removed by ordinary soil adsorption.
Chlorine is produced industrially by electrolysis of brine, usually together with sodium hydroxide, NaOH, and hydrogen, H₂, in the chlor-alkali process. The economics are closely tied to demand for caustic soda and for chlorine-consuming products such as polyvinyl chloride and isocyanates. Because chlorine gas is hazardous to transport, large users are often integrated with production sites or consume it nearby. Recycling is indirect: chloride from wastes may be recovered in salts or converted through industrial processes, but much chlorine ultimately disperses as chloride.
In nature it is found in the combined state only, chiefly with sodium as common salt (NaCl), carnallite, and sylvite.
Chlorine is a moderately abundant cosmic element made mainly in massive stars and supernova-related nucleosynthesis. It is less abundant than neighboring elements such as sulfur and argon. In planetary materials it is strongly lithophile and volatile relative to many rock-forming elements, occurring as chlorides, brines, and volcanic gases. Chlorine-bearing salts have been detected or inferred on several planetary bodies.
- Chlorine gas was used as a chemical weapon in the First World War.
- Natural chlorine has a stable isotope ratio that is useful in isotope geochemistry.
- Dry chlorine is less corrosive to many metals than moist chlorine.
- Common table salt contains chlorine as chloride, not as elemental Cl₂.
- Perchlorate salts can persist in arid soils and interfere with iodide uptake.
- Chlorine is liquefied commercially for storage and transport under pressure.
Images
Properties
Physical
- Atomic radius (empirical)
- 100 pm Compare Atomic radius (empirical) of all elements →
- Covalent radius
- 102 pm Compare Covalent radius of all elements →
- Van der Waals radius
- 175 pm Compare Van der Waals radius of all elements →
- Density
- 3.214 kg/m³ Compare Density of all elements →
- Molar volume
- 0.0187 L/mol
- Phase at STP
- Gas Compare Phase at STP of all elements →
- Melting point
- -101.5 °C Compare Melting point of all elements →
- Boiling point
- -34.04 °C Compare Boiling point of all elements →
- Thermal conductivity
- 0.009 W/(m·K) Compare Thermal conductivity of all elements →
- Specific heat capacity
- 0.479 J/(g·K) Compare Specific heat capacity of all elements →
- Molar heat capacity
- 33.949 J/(mol·K) Compare Molar heat capacity of all elements →
- Crystal structure
- Orthorhombic Compare Crystal structure of all elements →
Chemical
- Electronegativity (Pauling)
- 3.16 Compare Electronegativity (Pauling) of all elements →
- Electronegativity (Allen)
- 2.869
- Electron affinity
- 3.6127 eV
- Ionization energy (1st)
- 12.967633 eV Compare Ionization energy (1st) of all elements →
- Ionization energy (2nd)
- 23.813722 eV Compare Ionization energy (2nd) of all elements →
- Ionization energy (3rd)
- 39.800137 eV Compare Ionization energy (3rd) of all elements →
- Ionization energy (4th)
- 53.240183 eV Compare Ionization energy (4th) of all elements →
- Ionization energy (5th)
- 67.680233 eV Compare Ionization energy (5th) of all elements →
- Oxidation states
- −1, +1, +2, +3, +4, +5, +6, +7 Compare Oxidation states of all elements →
- Valence electrons
- 7 Compare Valence electrons of all elements →
- Electron configuration
- [Ne] 3s2 3p5
Thermodynamic
- Critical point (temperature)
- 143.9 °C
- Critical point (pressure)
- 7.991e+6 Pa
- Heat of fusion
- 0.0664352 eV Compare Heat of fusion of all elements →
- Heat of vaporization
- 0.21153547 eV Compare Heat of vaporization of all elements →
- Heat of atomization
- 1.261129 eV
- Atomization enthalpy
- 1.257211 eV
Nuclear
- Protons
- 17 Compare Protons of all elements →
- Neutrons
- 18 Compare Neutrons of all elements →
- Known isotopes
- 25 Compare Known isotopes of all elements →
- Stable isotopes
- 2 Compare Stable isotopes of all elements →
- Most stable isotope
- Cl-35
- Discovery year
- 1774
Abundance
- Abundance (Earth's crust)
- 145 mg/kg Compare Abundance (Earth's crust) of all elements →
- Abundance (ocean)
- 1.94 × 104 mg/L Compare Abundance (ocean) of all elements →
Crystal Structure
- Lattice constant a
- 624 pm
Electronic Structure
- Electrons per shell
- 2, 8, 7 Compare Electrons per shell of all elements →
Identifiers
- CAS number
- 7782-50-5 Compare CAS number of all elements →
- Term symbol
- 2P°3/2
- InChI
- InChI=1S/Cl
- InChI Key
- ZAMOUSCENKQFHK-UHFFFAOYSA-N
Electron Configuration Measured
Cl: 3s² 3p⁵[Ne] 3s² 3p⁵1s² 2s² 2p⁶ 3s² 3p⁵Atomic model
Isotopes change neutron count, mass, and stability — not the electron configuration of a neutral atom.
Schematic atomic model, not to scale.
Atomic Fingerprint
Emission / Absorption Spectrum
Isotope Distribution
| Mass number | Atomic mass (u) | Natural abundance | Half-life |
|---|---|---|---|
| 35 Stable | 34.968852682 ± 0.000000037 | 75.7600% | Stable |
| 37 Stable | 36.965902602 ± 0.000000055 | 24.2400% | Stable |
Phase / State
Reason: 59.0 °C above boiling point (-34.04 °C)
Schematic, not to scale
Phase transition points
Transition energies
Energy required to melt 1 mol at melting point
Energy required to vaporize 1 mol at boiling point
Density
At standard conditions
Estimated via ideal gas law at current T
Advanced
Atomic Spectra
Showing 10 of 17. Sorted by ion charge (ascending).
Lines Holdings ?
| Ion | Charge | Total lines | Transition probabilities | Level designations |
|---|---|---|---|---|
| Cl I | 0 | 221 | 99 | 100 |
| Cl II | +1 | 292 | 221 | 221 |
| Cl III | +2 | 192 | 166 | 166 |
| Cl IV | +3 | 73 | 42 | 45 |
| Cl V | +4 | 27 | 6 | 6 |
| Cl VI | +5 | 1 | 1 | 1 |
| Cl VII | +6 | 28 | 28 | 28 |
| Cl VIII | +7 | 5 | 5 | 5 |
| Cl IX | +8 | 3 | 3 | 3 |
| Cl X | +9 | 11 | 11 | 11 |
Levels Holdings ?
| Ion | Charge | Levels |
|---|---|---|
| Cl I | 0 | 379 |
| Cl II | +1 | 275 |
| Cl III | +2 | 83 |
| Cl IV | +3 | 41 |
| Cl V | +4 | 29 |
| Cl VI | +5 | 67 |
| Cl VII | +6 | 47 |
| Cl VIII | +7 | 29 |
| Cl IX | +8 | 57 |
| Cl X | +9 | 15 |
Ionic Radii
| Charge | Coordination | Spin | Radius |
|---|---|---|---|
| -1 | 6 | N/A | 181 pm |
| +5 | 3 | N/A | 12 pm |
| +7 | 4 | N/A | 8 pm |
| +7 | 6 | N/A | 27 pm |
Compounds
Isotopes (2)
| Mass number | Atomic mass (u) | Natural abundance | Half-life | Decay mode | |
|---|---|---|---|---|---|
| 35 Stable | 34.968852682 ± 0.000000037 | 75.7600% ± 0.1000% | Stable | stable | |
| 37 Stable | 36.965902602 ± 0.000000055 | 24.2400% ± 0.1000% | Stable | stable |
Spectral Lines
Showing 50 of 207. Only spectral lines with measured intensity are shown by default.
| Wavelength (nm) | Intensity | Ion stage | Type | Transition | Accuracy | Source | |
|---|---|---|---|---|---|---|---|
| 479.4556 nm | 99000 | Cl II | emission | 3s2.3p3.(4S*).4s 5S* → 3s2.3p3.(4S*).4p 5P | Measured | NIST | |
| 542.3257 nm | 99000 | Cl II | emission | 3s2.3p3.(4S*).3d 5D* → 3s2.3p3.(4S*).4p 5P | Measured | NIST | |
| 489.6783 nm | 81000 | Cl II | emission | 3s2.3p3.(2D*).4s 3D* → 3s2.3p3.(2D*).4p 3F | Measured | NIST | |
| 521.7945 nm | 56000 | Cl II | emission | 3s2.3p3.(4S*).4s 3S* → 3s2.3p3.(4S*).4p 3P | Measured | NIST | |
| 490.4776 nm | 47000 | Cl II | emission | 3s2.3p3.(2D*).4s 3D* → 3s2.3p3.(2D*).4p 3F | Measured | NIST | |
| 481.007 nm | 29000 | Cl II | emission | 3s2.3p3.(4S*).4s 5S* → 3s2.3p3.(4S*).4p 5P | Measured | NIST | |
| 491.773 nm | 26000 | Cl II | emission | 3s2.3p3.(2D*).4s 3D* → 3s2.3p3.(2D*).4p 3F | Measured | NIST | |
| 507.8267 nm | 26000 | Cl II | emission | 3s2.3p3.(2D*).4s 3D* → 3s2.3p3.(2D*).4p 3D | Measured | NIST | |
| 386.0828 nm | 25000 | Cl II | emission | 3s2.3p3.(4S*).4p 5P → 3s2.3p3.(4S*).4d 5D* | Measured | NIST | |
| 522.1362 nm | 23000 | Cl II | emission | 3s2.3p3.(4S*).4s 3S* → 3s2.3p3.(4S*).4p 3P | Measured | NIST | |
| 544.3375 nm | 19000 | Cl II | emission | 3s2.3p3.(4S*).3d 5D* → 3s2.3p3.(4S*).4p 5P | Measured | NIST | |
| 481.948 nm | 16000 | Cl II | emission | 3s2.3p3.(4S*).4s 5S* → 3s2.3p3.(4S*).4p 5P | Measured | NIST | |
| 539.2125 nm | 15000 | Cl II | emission | 3s2.3p3.(2D*).4s 1D* → 3s2.3p3.(2D*).4p 1F | Measured | NIST | |
| 478.132 nm | 13000 | Cl II | emission | 3s2.3p3.(2P*).4s 3P* → 3s2.3p3.(2P*).4p 3D | Measured | NIST | |
| 385.0988 nm | 10000 | Cl II | emission | 3s2.3p3.(4S*).4p 5P → 3s2.3p3.(4S*).4d 5D* | Measured | NIST | |
| 499.5473 nm | 10000 | Cl II | emission | 3s2.3p3.(2D*).3d 3F* → 3s2.3p3.(2D*).4p 3D | Measured | NIST | |
| 542.3516 nm | 10000 | Cl II | emission | 3s2.3p3.(4S*).3d 5D* → 3s2.3p3.(4S*).4p 5P | Measured | NIST | |
| 544.4217 nm | 10000 | Cl II | emission | 3s2.3p3.(4S*).3d 5D* → 3s2.3p3.(4S*).4p 5P | Measured | NIST | |
| 385.1374 nm | 7900 | Cl II | emission | 3s2.3p3.(4S*).4p 5P → 3s2.3p3.(4S*).4d 5D* | Measured | NIST | |
| 725.6618 nm | 7500 | Cl I | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).4p 4S* | Measured | NIST | |
| 545.7037 nm | 5600 | Cl II | emission | 3s2.3p3.(4S*).3d 5D* → 3s2.3p3.(4S*).4p 5P | Measured | NIST | |
| 741.4118 nm | 5000 | Cl I | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).4p 2P* | Measured | NIST | |
| 386.099 nm | 4400 | Cl II | emission | 3s2.3p3.(4S*).4p 5P → 3s2.3p3.(4S*).4d 5D* | Measured | NIST | |
| 476.8651 nm | 4300 | Cl II | emission | 3s2.3p3.(2P*).4s 3P* → 3s2.3p3.(2P*).4p 3D | Measured | NIST | |
| 384.5639 nm | 3900 | Cl II | emission | 3s2.3p3.(4S*).4p 5P → 3s2.3p3.(4S*).4d 5D* | Measured | NIST | |
| 384.5362 nm | 3100 | Cl II | emission | 3s2.3p3.(4S*).4p 5P → 3s2.3p3.(4S*).4d 5D* | Measured | NIST | |
| 380.5174 nm | 1900 | Cl II | emission | 3s2.3p3.(2D*).4p 3D → 3s2.3p3.(2D*).4d 3F* | Measured | NIST | |
| 609.468 nm | 1900 | Cl II | emission | 3s2.3p3.(2D*).4s 1D* → 3s2.3p3.(2D*).4p 1P | Measured | NIST | |
| 384.5788 nm | 1500 | Cl II | emission | 3s2.3p3.(4S*).4p 5P → 3s2.3p3.(4S*).4d 5D* | Measured | NIST | |
| 391.3866 nm | 1500 | Cl II | emission | 3s2.3p3.(2D*).4p 3F → 3s2.3p3.(2D*).4d 3F* | Measured | NIST | |
| 380.9459 nm | 1300 | Cl II | emission | 3s2.3p3.(2D*).4p 3D → 3s2.3p3.(2D*).4d 3F* | Measured | NIST | |
| 385.1651 nm | 1200 | Cl II | emission | 3s2.3p3.(4S*).4p 5P → 3s2.3p3.(4S*).4d 5D* | Measured | NIST | |
| 391.6632 nm | 1100 | Cl II | emission | 3s2.3p3.(2D*).4p 3F → 3s2.3p3.(2D*).4d 3F* | Measured | NIST | |
| 386.1378 nm | 1000 | Cl II | emission | 3s2.3p3.(4S*).4p 5P → 3s2.3p3.(4S*).4d 5D* | Measured | NIST | |
| 399.1367 nm | 700 | Cl III | emission | 3s2.3p2.(3P).3d 4P → 3s2.3p2.(3P).4p 4P* | Measured | NIST | |
| 401.8351 nm | 600 | Cl III | emission | 3s2.3p2.(3P).3d 4P → 3s2.3p2.(3P).4p 4P* | Measured | NIST | |
| 405.893 nm | 600 | Cl III | emission | 3s2.3p2.(3P).3d 4P → 3s2.3p2.(3P).4p 4P* | Measured | NIST | |
| 410.4082 nm | 500 | Cl III | emission | 3s2.3p2.(3P).3d 4P → 3s2.3p2.(3P).4p 4P* | Measured | NIST | |
| 410.6764 nm | 500 | Cl III | emission | 3s2.3p2.(3P).3d 4P → 3s2.3p2.(3P).4p 4P* | Measured | NIST | |
| 436.3268 nm | 100 | Cl I | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).5p 4D* | Measured | NIST | |
| 436.9498 nm | 100 | Cl I | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).5p 2D* | Measured | NIST | |
| 437.9896 nm | 100 | Cl I | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).5p 4D* | Measured | NIST | |
| 438.9751 nm | 100 | Cl I | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).5p 4D* | Measured | NIST | |
| 443.8488 nm | 100 | Cl I | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).5p 4P* | Measured | NIST | |
| 452.6182 nm | 100 | Cl I | emission | 3s2.3p4.(3P).4s 2P → 3s2.3p4.(3P).5p 2P* | Measured | NIST | |
| 439.0403 nm | 90 | Cl I | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).5p 4D* | Measured | NIST | |
| 440.302 nm | 90 | Cl I | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).5p 4P* | Measured | NIST | |
| 447.5304 nm | 90 | Cl I | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).5p 2D* | Measured | NIST | |
| 460.0977 nm | 80 | Cl I | emission | 3s2.3p4.(3P).4s 2P → 3s2.3p4.(3P).5p 2P* | Measured | NIST | |
| 466.1208 nm | 80 | Cl I | emission | 3s2.3p4.(3P).4s 2P → 3s2.3p4.(3P).5p 2P* | Measured | NIST |
Extended Properties
Covalent Radii (Extended)
- Covalent radius (Pyykkö)
- 99 pm
- Covalent radius (Pyykkö, double)
- 95 pm
- Covalent radius (Pyykkö, triple)
- 93 pm
- Covalent radius (Bragg)
- 105 pm
Van der Waals Radii
- Bondi
- 175 pm
- Batsanov
- 180 pm
- Alvarez
- 182 pm
- UFF
- 394.7 pm
- MM3
- 207 pm
- Dreiding
- 395.03 pm
- Rowland–Taylor
- 176 pm
Atomic & Metallic Radii
- Atomic radius (Rahm)
- 206 pm
- Metallic radius (C12)
- 91 pm
Numbering Scales
- Mendeleev
- 107
- Pettifor
- 99
- Glawe
- 101
Electronegativity Scales
- Ghosh
- 0
- Gunnarsson–Lundqvist
- 9
- Robles–Bartolotti
- 8
Polarizability & Dispersion
- Dipole polarizability
- 14.6 a.u.
- Dipole polarizability (unc.)
- 0.1 a.u.
- C₆
- 94.6 Ha·Bohr6
- C₆ (Gould–Bučko)
- 97.1 Ha·Bohr6
Chemical Affinity
- Proton affinity
- 513.6 kJ/mol
- Gas basicity
- 490.1 kJ/mol
Supply Risk & Economics
- Production concentration
- 24
- Relative supply risk
- 4
- Political stability (top producer)
- 24
Phase Transitions & Allotropes
| Melting point | 171.65 K |
| Boiling point | 239.11 K |
| Critical point (temperature) | 417.05 K |
| Critical point (pressure) | 7.99 MPa |
Oxidation State Categories
Advanced Reference Data
Screening Constants (5)
| n | Orbital | σ |
|---|---|---|
| 1 | s | 0.4761 |
| 2 | p | 4.0068 |
| 2 | s | 5.5696 |
| 3 | p | 10.8839 |
| 3 | s | 9.9317 |
Crystal Radii Detail (4)
| Charge | CN | Spin | rcrystal (pm) | Origin |
|---|---|---|---|---|
| -1 | VI | 167 | Pauling's (1960) crystal radius, | |
| 5 | IIIPY | 26 | ||
| 7 | IV | 22 | ||
| 7 | VI | 41 | Ahrens (1952) ionic radius, |
Isotope Decay Modes (45)
| Isotope | Mode | Intensity |
|---|---|---|
| 28 | p | 100% |
| 29 | p | 100% |
| 30 | p | 100% |
| 31 | B+ | 100% |
| 31 | B+p | 2.4% |
| 32 | B+ | 100% |
| 32 | B+A | 0.1% |
| 32 | B+p | 0% |
| 33 | B+ | 100% |
| 34 | B+ | 100% |
X‑ray Scattering Factors (504)
| Energy (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 1.46938 |
| 10.1617 | — | 1.6922 |
| 10.3261 | — | 1.9488 |
| 10.4931 | — | 2.24432 |
| 10.6628 | — | 2.51303 |
| 10.8353 | — | 2.73153 |
| 11.0106 | — | 2.95549 |
| 11.1886 | — | 3.19416 |
| 11.3696 | — | 3.48881 |
| 11.5535 | — | 3.87618 |
Additional Data
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
1.45×102 milligrams per kilogram
References (1)
- [5] Chlorine https://education.jlab.org/itselemental/ele017.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
1.94×104 milligrams per liter
References (1)
- [5] Chlorine https://education.jlab.org/itselemental/ele017.html
Sources
Sources of this element.
In nature it is found in the combined state only, chiefly with sodium as common salt (NaCl), carnallite, and sylvite.
References (1)
- [6] Chlorine https://periodic.lanl.gov/17.shtml
Isotopes in Forensic Science and Anthropology
Information on the use of this element's isotopes in forensic science and anthropology.
Analyses of chlorine isotopes and other environmental tracers can help to identify whether an environmental contaminant is of anthropogenic origin or naturally occurring. For example, perchlorate (ClO4 -) can be of anthropogenic origin and is also found naturally. Perchlorate is a widespread groundwater contaminant that can interfere with hormone production in the thyroid gland by displacing iodide. Both the stable chlorine isotope-amount ratio n(37Cl)/n(35Cl) and the mole fraction of 36Cl, n(36Cl)/n(Cl), can provide useful information about origins of perchlorate in the environment (Fig. IUPAC.17.2). Such information may be important for legal reasons and for remediation of contaminated areas [152] M. A. Stewart, A. J. Spivack. Rev. Mineral. Geochem.55, 231 (2004)., [153] J. K. Böhlke, N. C. Sturchio, B. Gu, J. Horita, G. M. Brown, W. A. Jackson, J. R. Batista, P. B. Hatzinger. Anal. Chem.77, 7838 (2005)..
References (4)
- [152] M. A. Stewart, A. J. Spivack. Rev. Mineral. Geochem.55, 231 (2004).
- [153] J. K. Böhlke, N. C. Sturchio, B. Gu, J. Horita, G. M. Brown, W. A. Jackson, J. R. Batista, P. B. Hatzinger. Anal. Chem.77, 7838 (2005).
- [154] J. K. Böhlke, P. Hatzinger, N. C. Sturchio, B. Gu, I. J. Abbene, S. J. Mroczkowski. Environ. Sci. Technol.43, 5619 (2009).
- [4] IUPAC Periodic Table of the Elements and Isotopes (IPTEI) https://doi.org/10.1515/pac-2015-0703
References
(9)
Data deposited in or computed by PubChem
The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.
Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.
The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.
Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/
The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.
The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database
This section provides all form of data related to element Chlorine.
The element property data was retrieved from publications.