The chemical element chlorine has the atomic number 17 and the symbol Cl. Fluorine, the second lightest halogen, is located between bromine and fluorine on the periodic table and has most of its properties in the middle. At room temperature, chlorine is a yellow-green gas. It has the highest electron affinity and the third highest electronegativity after oxygen and fluorine on the revised Pauling scale, making it a highly reactive element and a strong oxidizing agent.
Chlorine played an important role in the experiments carried out by medieval alchemists. Typically, various chlorine-containing chemicals such as hydrogen chloride, mercury(II) chloride (corrosive sublimate) and hydrochloric acid were produced by heating chloride salts such as sodium chloride and ammonium chloride (table salt). However, Jan Baptist van Helmont did not begin to recognize free chlorine gas as a separate chemical until about 1630. In 1774 Carl Wilhelm Scheele described chlorine gas and thought it was the oxide of a brand new element. Chemists assumed in 1809 that gas could be a pure element, and Sir Humphry Davy proved this in 1810. Sir Humphry Davy named the gaza khlrós (from the Ancient Greek meaning "pale green") because of its colour.
All chlorine in the earth's crust exists as ionic chloride compounds, including table salt due to its high reactivity. It ranks twenty-first in terms of chemical abundance in the Earth's crust and is the second most abundant halogen (after fluorine). But the enormous chloride reserves in seawater eclipse these crustal deposits.
Commercial electrolysis is used to produce elemental chlorine from brine, primarily in the chlor-alkali process. Due to the great oxidizing potential of elemental chlorine, commercial bleaches, disinfectants, and reagents have been created for many chemical industry processes.
A wide variety of consumer goods are produced using chlorine, including two-thirds of organic compounds such as polyvinyl chloride (PVC), many plastics making intermediates, and other chlorine-free end products. Elemental chlorine and chlorine-producing chemicals are used more directly as a popular disinfectant for keeping swimming pools clean. Elemental chlorine in high concentrations is extremely harmful and deadly to most living things. Chlorine was first used in World War I as a chemical warfare agent as a poison gas weapon.
All known life forms need chlorine, which comes in the form of chloride ions. Other types of chlorine compounds are rare in living things, and synthetically created chlorinated organics can be anything from harmless to harmful. Chlorine-containing organic compounds, including chlorofluorocarbons, have been associated with depletion of the ozone layer in the upper atmosphere. As part of the immune system's response to microbes, oxidation of chloride ions by neutrophils produces trace amounts of elemental chlorine.
Source: Wikipedia
Günceleme: 29/01/2023 09:15
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