Chlorine

Chlorine
W. Oelen · CC BY-SA 3.0 · source
Name	Chlorine
Atomic number	17
Atomic weight	35.45
Appearance	Greenish-yellow gas
State at room temp	Gas
Group	17
Electron configuration	[Ne] 3s2 3p5

Chlorine Chlorine is a halogen element with atomic number 17, notable as a reactive diatomic gas used across industry, sanitation, and chemical synthesis. It plays critical roles in processes linked to companies and institutions such as Dow Chemical Company, BASF, and DuPont, and intersects with regulatory frameworks from bodies like the Environmental Protection Agency and the European Chemicals Agency. Chlorine’s reactivity and ubiquity have influenced public health initiatives, industrial development, and environmental debates involving actors including World Health Organization and United Nations Environment Programme.

Introduction

Chlorine appears in elemental form as a diatomic molecule and in myriad compounds, including salts like sodium chloride used by Royal Navy-era navies and modern suppliers such as Cargill; oxidizers such as hypochlorite produced by firms like Olin Corporation; and organochlorines manufactured historically by corporations like Monsanto and Union Carbide. Its industrial relevance connects to sectors served by entities such as General Electric and Siemens AG, and to historical developments involving chemists such as Humphry Davy and Carl Wilhelm Scheele.

Physical and Chemical Properties

Elemental chlorine is a yellow-green gas at ambient conditions, with a pungent odor and a density greater than air; these properties affect handling by organizations like Occupational Safety and Health Administration and National Institute for Occupational Safety and Health. As a strong oxidizing agent, chlorine reacts vigorously with hydrogen, hydrocarbons, and ammonia—reactions studied in contexts involving research institutions including Massachusetts Institute of Technology and ETH Zurich. Chlorine’s electron configuration leads to a high electronegativity influencing bond energies in chlorinated compounds examined in literature from Royal Society of Chemistry and textbooks from publishers such as Oxford University Press.

Occurrence and Production

Chlorine is abundant in Earth's crust as chloride minerals like halite mined by companies including Compass Minerals and K+S. Commercial production uses electrolysis of brine in cell technologies originally developed and scaled by firms like W. R. Grace and Company and improved in partnerships with engineering firms such as KBR, Inc.. Major production hubs have included regions serviced by corporations like ExxonMobil and Shell plc, while global supply chains and trading involve entities such as Glencore and Vitol.

Applications and Uses

Chlorine-based compounds underpin water disinfection practices promoted by World Health Organization and implemented by municipal utilities such as Metropolitan Water District of Southern California; industrial chemistry processes at companies like BASF produce polyvinyl chloride used by manufacturers such as ArcelorMittal and in construction projects by firms like Bechtel. Agrochemical applications once developed by Bayer AG and others produced chlorinated pesticides; pharmaceutical syntheses in corporations like Pfizer and Novartis utilize chlorinated intermediates. Other sectors using chlorine chemistry include paper and pulp mills run by firms such as International Paper, and semiconductor fabrication lines at companies including Intel Corporation.

Biological Effects and Toxicology

Exposure to elemental chlorine or its high-concentration compounds has acute respiratory and ocular effects documented in case reports from medical centers such as Mayo Clinic and publications by Centers for Disease Control and Prevention. Occupational exposure limits are enforced following guidelines from Occupational Safety and Health Administration and research by National Institute for Occupational Safety and Health, with clinical management protocols taught in curricula at institutions like Johns Hopkins University and Harvard Medical School. Chronic exposure to certain organochlorines has been studied in epidemiological investigations coordinated by groups such as National Institutes of Health and reported in cohort studies from universities including University of California, Berkeley.

Environmental Impact and Regulation

Chlorine chemistry has produced persistent pollutants investigated in international agreements and regulatory actions involving Stockholm Convention on Persistent Organic Pollutants, European Commission, and national agencies like the Environmental Protection Agency. Releases from industrial incidents have led to emergency responses coordinated by agencies such as Federal Emergency Management Agency and cross-border dialogues mediated by United Nations Environment Programme. Remediation technologies developed by firms like CH2M Hill and academic groups at Imperial College London address contamination in soils and waterways, while lifecycle analyses from organizations like International Energy Agency inform policy.

History and Discovery

Chlorine’s identification emerged from experiments by Carl Wilhelm Scheele and later nomenclature and isolation work influenced by Sir Humphry Davy; industrial electrochemical production was advanced during the 19th and 20th centuries alongside chemical firms such as Henkel and trade networks tied to British East India Company-era saltworks. Military and civil uses—ranging from early sanitation efforts promoted by public health figures like John Snow to wartime incidents involving chemical agents in contexts such as World War I—shaped public perception and regulation enforced by bodies including League of Nations and later United Nations frameworks.

Category:Chemical elements