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Author: langbot
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English[en]
Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest halogen and is a volatile red-brown liquid at room temperature that evaporates readily to form a similarly coloured vapour. Its properties are intermediate between those of chlorine and iodine. Isolated independently by two chemists, Carl Jacob Löwig (in 1825) and Antoine Jérôme Balard (in 1826), its name was derived from the Ancient Greek βρῶμος (meaning "stench"), referring to its sharp and pungent smell. Elemental bromine is very reactive and thus does not occur free in nature, but in colourless soluble crystalline mineral halide salts, analogous to table salt. While it is rather rare in the Earth's crust, the high solubility of the bromide ion (Br−) has caused its accumulation in the oceans. Commercially the element is easily extracted from brine evaporation ponds, mostly in the United States, Israel, and China. The mass of bromine in the oceans is about one three-hundredth that of chlorine. At standard conditions for temperature and pressure it is a liquid; the only other element that is liquid under these conditions is mercury. At high temperatures, organobromine compounds readily dissociate to yield free bromine atoms, a process that stops free radical chemical chain reactions. This effect makes organobromine compounds useful as fire retardants, and more than half the bromine produced worldwide each year is put to this purpose. The same property causes ultraviolet sunlight to dissociate volatile organobromine compounds in the atmosphere to yield free bromine atoms, causing ozone depletion. As a result, many organobromine compounds—such as the pesticide methyl bromide—are no longer used. Bromine compounds are still used in well drilling fluids, in photographic film, and as an intermediate in the manufacture of organic chemicals. Large amounts of bromide salts are toxic from the action of soluble bromide ions, causing bromism. However, a clear biological role for bromide ions and hypobromous acid has recently been elucidated, and it now appears that bromine is an essential trace element in humans. The role of biological organobromine compounds in sea life such as algae has been known for much longer. As a pharmaceutical, the simple bromide ion (Br−) has inhibitory effects on the central nervous system, and bromide salts were once a major medical sedative, before replacement by shorter-acting drugs. They retain niche uses as antiepileptics.
Cornish[kw]
Elven gymyk yw bromin, niver 35 y'n Vosen Beriodek. Y furvell yw Br. An hanow a dheu dhyworth an ger Greka bromos, ow styrya fler. Peryllus ha dasoberus yw bromin. Pur gesknius yw, hag y ethen owth omsettya war lagasow ha skevens. Fest gwenonek yw, le ages 100mg yw dogen merwel. Nyns eus gans bromin rann bewoniethel. Y'n 19ves kansvledhen, medhogyon a worhemynna holanow bromid rag kudynnow nervus (hevelep dhe galmydhyon ens rag pobel Victorian). Ny worhemynnys yns lemmyn drefen aga bos nebes gwenonek. Antoine-Jerôme Balard (1802-1876) a dhiskudhas bromin yn 1826 yn Montpelier, Pow Frynk. Ev a vynnas an hanow muride, mes an Akademi Frynkek a erviras war an hanow bromin. Tennys yw bromin yn mes a dhowr an mor yn diwysyansek. Y'n termyn eus passyes askorrys o bromin yn Kembra, war Enys Môn. Ysrael a askorr meur anedha drefen halonekter an Mor Marow. Usys yw dhe wul kesstoffow organobromo, y'n diwysyansow ladher treghviles, yn difudhellow tan ha medhegieth. An devnydh a organobromin rag difudhellow tan ha methyl bromid rag plaladhoryon a leha drefen prederow a-dro dhe'n nivel ozon. Poos atomek bromin yw 79.90, an poynt teudhi yw -7°C ha'n poynt bryjyon yw 59°C. Y dhosedh yw 3.1kg an liter. Lin rudh fler yw bromin. Yth esa atomow bromin yn rann a'n liw usys dhe wul Tyrian purple. Kevys o an liw purpur dhyworth kregyn Murex, hag usys o gan emperours rag aga thogaow.