chlorine

Also known as Cl, element 17, bertholite, ₁₇Cl

Chlorine is a chemical element; it has symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is a yellow-green gas at room temperature. It is an extremely reactive element and a strong oxidising agent: among the elements, it has the highest electron affinity and the third-highest electronegativity on the revised Pauling scale, behind only oxygen and fluorine.

AI overview

Chlorine is a yellow-green gas and chemical element that sits between fluorine and bromine in the periodic table, with properties falling between those two elements. It is extremely reactive and a powerful oxidizing agent, ranking among the highest in the periodic table for electron affinity and electronegativity.

AI-generated from the Wikipedia summary — may contain errors.

Key facts

Chlorine.engvar: en-GB

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Research

68,257 papers

Chlorine cycling and the fate of Cl in terrestrial environments.ReviewEnvironmental science and pollution research international · 2021Svensson T, Kylin H, Montelius M et al.DOI: 10.1007/s11356-020-12144-6
A systematic review on chlorine tolerance among bacteria and standardization of their assessment protocol in wastewater.Water science and technology : a journal of the International Association on Water Pollution Research · 2022Gupta V, Shekhawat SS, Kulshreshtha NM et al.DOI: 10.2166/wst.2022.206
The Recurring Roles of Chlorine in Synthetic and Biological Studies of the Lissoclimides.ReviewAccounts of chemical research · 2021Pak BS, Supantanapong N, Vanderwal CDDOI: 10.1021/acs.accounts.0c00866
Environmental impacts of the widespread use of chlorine-based disinfectants during the COVID-19 pandemic.ReviewEnvironmental science and pollution research international · 2022Parveen N, Chowdhury S, Goel SDOI: 10.1007/s11356-021-18316-2
In Situ Preparation of Chlorine-Regenerable Antimicrobial Polymer Molecular Sieve Membranes.Molecules (Basel, Switzerland) · 2024Zhang Y, Qian Y, Wen Y et al.DOI: 10.3390/molecules29132980
Comparative analysis of chlorine-resistant bacteria after chlorination and chloramination in drinking water treatment plants.Journal of hazardous materials · 2024Wei Y, Wu H, Zhang X et al.DOI: 10.1016/j.jhazmat.2024.134075
Chlorine decay and disinfection by-products transformation under booster chlorination conditions: A pilot-scale study.The Science of the total environment · 2022Liao P, Zhang T, Fang L et al.DOI: 10.1016/j.scitotenv.2022.158115
UV/chlorine and chlorination of effluent organic matter fractions: Tracing nitrogenous DBPs using FT-ICR mass spectrometry.Water research · 2023Wang Y, Xiang Y, Marques Dos Santos M et al.DOI: 10.1016/j.watres.2023.119646

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Wikidata facts

Mass: 35.45
Image: Chlorine liquid in an ampoule.jpg

Show 11 more facts

oxidation state: 7
element symbol: Cl
Commons category: Chlorine
atomic number: 17
Commons gallery: Chlorine
ionization energy: 11.48
electronegativity: 3
time of discovery or invention: 1774-00-00
electron configuration: 1s² 2s² 2p⁶ 3s² 3p⁵
ionic radius: 0.08
Unicode character: 氯

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~61 min read

Article

36 sections

Contents

History
Early discoveries
Isolation
Later uses
Properties
Isotopes
Chemistry and compounds
Hydrogen chloride
Other binary chlorides
Polychlorine compounds
Chlorine fluorides
Chlorine oxides
Chlorine oxoacids and oxyanions
Organochlorine compounds
Occurrence
Production
Chloralkali processes
Non-chloralkali processes
Applications
Sanitation, disinfection, and antisepsis
Combating putrefaction
Disinfection
Semmelweis and experiments with antisepsis
Public sanitation
Use as a weapon
World War I
Middle East
Biological role
Hazards
Chlorine-induced cracking in structural materials
Chlorine–iron fire
See also
Notes
References
Bibliography
External links

Chlorine played an important role in the experiments conducted by medieval alchemists, which commonly involved the heating of chloride salts like ammonium chloride (sal ammoniac) and sodium chloride (common salt), producing various chemical substances containing chlorine such as hydrogen chloride, mercury(II) chloride (corrosive sublimate), and . However, the nature of free chlorine gas as a separate substance was only recognised around 1630 by Jan Baptist van Helmont. Carl Wilhelm Scheele wrote a description of chlorine gas in 1774, supposing it to be an oxide of a new element. In 1809, chemists suggested that the gas might be a pure element, and this was confirmed by Sir Humphry Davy in 1810, who named it after the Ancient Greek (, "pale green") because of its colour.