Halogen name comes from the Greek meaning dangenes halos forming salt.So named because these elements can react with metal elements to form salts.
Swedish chemist Baron Jons Jakob Berzelius mengistilahkan "Halogen" - Alphaλς (Hals), "salt" or "sea", and γεν- (gene-), from γίγνομαι (gígnomai), "form" - the elements that form salts when reacted with metal.
In the periodic system, halogen element contained in a vertical row group VIIA (or 17 in the numbering of new groups),
Electron configuration thus making the halogen elements are very reactive and tend to absorb a single electron to form a negatively charged ion.Consequently halogen elements not found in the state of monatomic in nature, but can be bonded to form the halogen compounds with other elements, or with other elements of both metal and non-metallic.
Halogen elements are naturally shaped molecules of diatomic.They need an extra electron to fill the electron orbits the outer, so it tends to form ion negatively charged one. Negative ions are called ionic halides, and salts formed by ions are called halides.The stability of halogen molecules is reduced daari Cl2 to I2.This is because the accretion radius of the atom.Thus, its binding energy decreases.Especially for the fluorine atom which has a bond energy <of Cl due to the small atomic radius so that, inter-core repulsive inter-atomic and free electron pair to be great.So, from this we can conclude why fluorine is very reactive.
History of discovery Halogen
fluorine (F) is found in Flourspar by Schwandhard in 1970 and in
1886 Ferdinand of Francis Hendy Moissan succeeded membuar fluorine gas through a process Electrolysis.
Chlorine (Cl) was found by Schele in 1974 was named by Davy in the year
Bromine (Br) discovered by Balard in 1826.Bromine is a liquid substance bewarna
reddish brown easily evaporate at room temperature, the vapor colored red.
Bromine is less reactive than Clor.
Iodine (I) was discovered by Courtois in 1811.
Astatine (At) was discovered by DR. Corson, KR Mackenzie, and E. Segre in 1940.
Astatine is a radioactive substance is first made as a result of the bombing of Bismuth
In nature, not in the state of halogen-free, but always in a state as a compound, because of its reactivity.In general, the halogen is in a state as a compound with oxidation number -1 (halides).These elements found in nature as the compound salt.Fluorine contained in flourit (Ca F₂) and Kriolit (Na₃ALF6).Chlorine present in sea water as NaCl.In the form of chloride ions, these elements are the building blocks of salt and other compounds available in nature in a number of very abundant and necessary for the formation of almost all life forms, including humans.Bromine is found as salts of sodium and magnesium.
Retrieved from natural brine springs in Michigan and Arkansas.Bromine is also extracted from sea water, with only content of 82 ppm.Iodine found in nature in the form of iodate and iodide compound in the lichen-moss sea.There is also in the form of iodide from seawater assimilated by seaweeds, Chile saltpeter, nitrate-rich soil (known as a dull, namely calcium carbonate sedimentary rocks that hard), saline water from sea water that is stored, and in brackish water from oil wells and salt.
Elemental fluorine and fluoride ion are highly toxic.Free element has a characteristic sharp odor, can be detected in concentrations as low as 20 ppb, which is below the level of security work.Concentration which allowed for exposure for 8 hours of work is 1 ppm.
In its pure form, he's very dangerous, can cause severe chemical burn is so associated with the skin.
Chlorine irritates the respiratory system.Gas irritates the mucus layer shape and form of liquid can burn the skin.The smell can be detected at concentrations as small as 3.5 ppm and at 1000 ppm is fatal after inhaled deeply. In fact, chlorine is used as a chemical weapon in the war gas in 1915.Exposed to chlorine should not exceed 0.5 ppm for 8 hours a day, 40 hours per week.
A chemical element in the periodic table has the symbolFandatomic number9.The name comes fromthe Latinfluere, meaning "flowing".He is a gashalogenunivalentpoisonous, yellow-green of the most chemically reactive andelectronegativeof all elements.In its pure form, he's very dangerous, can cause severe chemical burn is so associated with the skin.
Chlorine(Greek:Chloros, "pale green"), is achemical elementwith symbolCland atomic number 17.In theperiodic table, these elements including the grouphalogenor group 17 (old system: VII or VIIA).In the form ofionchloride, this element is formingsaltsand other compounds available in nature in a number of very abundant and necessary for the formation of almost all forms of life.
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