Cl
Chlorum
CHLORINE
HALOGENS ELEMENT
| Atomic number: | 17 |
| Group numbers: | 17 |
| Period: | 3 |
| Electronic configuration: | [Ne] 3s2 3p5 |
| Formal oxidation number: | -1 +1 +5 +7 |
| Electronegativities: | 3.16 |
| Atomic radius / pm: | 99.4 |
| Relative atomic mass: | [35.446, 35.457] |
Chlorine was discovered by Carl William Scheele (SE) in 1774. The origin of the name comes from the Greek word chloros meaning pale green. It is a greenish-yellow, disagreeable gas with irritating odour. The gas is toxic and severe irritant by contact or inhalation. It's Never found in free form in nature. Commercial quantities of chlorine are produced by electrolysis of aqueous sodium chloride (NaCl) from seawater or brine from salt mines. Sulfur is used in water purification, bleaches, acids and many, many other compounds such as chlorofluorocarbons (CFC).
| Density / g dm-3: | 2030 | (113 K) |
| 1507 | (239 K) | |
| 3.214 | (273 K) | |
| Molar volume / cm3mol-1: | 17.46 | (113 K) |
| 23.53 | (239 K) | |
| 22061.61 | (273 K) | |
| Electrical resistivity / µΩcm: | - | (20 °C) |
| Thermal conductivity / W m-1K-1: | 0.0089 |
| Melting point / °C: | -101.5 |
| Boiling point / °C: | -34.04 |
| Heat of fusion / kJ mol-1: | 6.41 |
| Heat of vaporization / kJ mol-1: | 20.4033 |
| Heat of atomization / kJ mol-1: | 120 |
| First ionization energy / kJ mol-1: | 1251.20 |
| Second ionization energy / kJ mol-1: | 2297.72 |
| Third ionization energy / kJ mol-1: | 3821.81 |
| in the atmosphere / ppm: | - |
| in the Earth's crust / ppm: | 130 |
| in the oceans / ppm: | 19000 |
| Crystal structure: | base-centered orthorhombic |
| Unit-cell dimensions / pm: | a=624, b=448, c=826 |
| Space group: | Cmca |
| Isotope | Relative atomic mass | Mass percent (%) |
|---|---|---|
| 35Cl | 34.96885271(4) | 75.77(7) |
| 37Cl | 36.96590260(5) | 24.23(7) |
| Balanced half-reaction | Eo / V | |
|---|---|---|
| Cl2(g) + 2e- → 2Cl- | +1.359 | |
| Cl2(aq) + 2e- → 2Cl- | +1.39 | |
| ClO4- + 2H+ + 2e- → ClO3- + H2O | +1.19 | |
| ClO4- + H2O + 2e- → ClO3- + 2OH- | +0.36 | |
| 2ClO4- + 16H+ + 14e- → Cl2(g) + 8H2O | +1.39 | |
| ClO3- + 3H+ + 2e- → HClO2 + H2O | +1.21 | |
| ClO3- + H2O + 2e- → ClO2- + 2OH- | +0.33 | |
| 2ClO3- + 12H+ + 10e- → Cl2(g) + 3H2O | +1.47 | |
| HClO2 + 2H+ + 2e- → HClO + H2O | +1.64 | |
| ClO2- + H2O + 2e- → ClO- + 2OH- | +0.66 | |
| 2HClO + 2H+ + 2e- → Cl2(g) + H2O | +1.63 | |
| 2ClO- + 2H2O + 2e- → Cl2(g) + 4OH- | +0.40 |
| 16 Sulphur | ← | 17 Chlorine | → | 18 Argon |
Citing this page:
Generalic, Eni. "Chlorine." EniG. Periodic Table of the Elements. KTF-Split, 13 Feb. 2025. Web. {Date of access}. <https://www.periodni.com/cl.html>.
Copyright © 1998-2025 by Eni Generalic. All rights reserved. | Bibliography | Disclaimer