Cleaning with bleach could create indoor air pollutants

For generations, people have used chlorine bleach to clean and disinfect their homes. However, researchers have now discovered that bleach fumes, in combination with light and a citrus compound found in many household products, ...

Climate change in the Southern Hemisphere

On its mission "SouthTRAC," the German research aircraft HALO will investigate the southern atmosphere and its effects on climate change in September and November 2019. Researchers from Goethe University will also be on board.

Why is the Earth's F/Cl ratio not chondritic?

Primitive chondrites, un-molten stony meteorites, are believed to be the building blocks of the Earth. Because terrestrial planets have experienced chemical differentiation in the core, mantle, and hydrosphere, the elemental ...

Diving into water treatment strategies for swimming pools

With summer in full swing, many people are cooling off in swimming pools. However, some of the substances that are made when chlorine in the water reacts with compounds in human sweat, urine or dirt aren't so refreshing. ...

Progress in hunt for unknown compounds in drinking water

An unknown number of byproducts are formed in the drinking water treatment process, and scientists don't know what many of them are. However, using advanced technology, researchers at Linköping University have been able ...

A step closer to sustainable energy from seawater

The research group led by Leiden chemist Marc Koper has discovered a catalyst that minimizes the production of chlorine gas during salt water electrolysis. The invention can enable the direct production of hydrogen from seawater. ...

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Chlorine

Chlorine ( /ˈklɔəriːn/ klohr-een; from Ancient Greek: χλωρóς khlôros "pale green") is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine. It has the highest electron affinity and the third highest electronegativity of all the elements; for this reason, chlorine is a strong oxidizing agent.

The most common compound of chlorine, sodium chloride, has been known since ancient times; however, around 1630, chlorine gas was obtained by the Belgian chemist and physician Jan Baptist van Helmont. The synthesis and characterization of elemental chlorine occurred in 1774 by Swedish chemist Carl Wilhelm Scheele, who called it "dephlogisticated muriatic acid air," having thought he synthesized the oxide obtained from the hydrochloric acid. Because acids were thought at the time to necessarily contain oxygen, a number of chemists, including Claude Berthollet, suggested that Scheele's dephlogisticated muriatic acid air must be a combination of oxygen and the yet undiscovered element, and Scheele named the supposed new element within this oxide as muriaticum. The suggestion that this newly discovered gas was a simple element was made in 1809 by Joseph Louis Gay-Lussac and Louis-Jacques. This was confirmed by Sir Humphry Davy in 1810, who named it chlorine, from the Greek word χλωρος (chlōros), meaning "green-yellow."

Chlorine is a component of various compounds, including table salt. It is the second most abundant halogen and 21st most abundant chemical element in Earth's crust. The great oxidizing potential of chlorine led it to its bleaching and disinfectant uses, as well as uses of an essential reagent in the chemical industry. As a common disinfectant, chlorine compounds are used in swimming pools to keep them clean and sanitary. In the upper atmosphere, chlorine-containing molecules such as chlorofluorocarbons have been implicated in ozone depletion. Elemental chlorine is extremely dangerous and poisonous for all lifeforms; however, chlorine is necessary to most forms of life, including humans, in form of chloride ions.

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