Halogen HISTORY
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.
Electrolysis.
Chlorine (Cl) was found by Schele in 1974 was named by Davy in the year
1810.
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
with alpha particles.
Halogen
Halogen is a group of chemical elements which is in group 17 (VII or VIIA of the old system) in the periodic table.
This group consists of: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and elements ununseptium (Uus) that have not been found. Signifies halogen elements which produce salt when reacted with the metal.
For example the reaction of salt:
Na+ + Cl- into NaClIn 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
Halogen HAZARD
Halogen HAZARD
Fluorine (F)
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.
Klour (Cl)
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.
Bromine (Br)
In liquid form, this substance is corrosive to tissue cells of human and fumes cause irritation to eyes and throat. In the form of gases, bromine is toxic.
THE TYPES OF ELEMENTS halogen
a. Fluorine
A chemical element in the periodic table has the symbol F and atomic number 9. The name comes from the Latin fluere, meaning "flowing". He is a gashalogen univalent poisonous, yellow-green of the most chemically reactive andelectronegative of all elements. In its pure form, he's very dangerous, can cause severe chemical burn is so associated with the skin.
b. Chlorine
Chlorine (Greek: Chloros, "pale green"), is a chemical element with symbol Cl and atomic number 17. In the periodic table, these elements including the group halogen or group 17 (old system: VII or VIIA). In the form of ion chloride, this element is forming saltsand other compounds available in nature in a number of very abundant and necessary for the formation of almost all forms of life.
c. Brom
Brom (Greek: βρωμος, brómos - smelling of urine), is a chemical element in the periodic table that has the symbol Br and atomic number 35. Elements of Chemical series halogens is shaped liquid red at room temperature and has a reactivity between chlorine and iodine.
d. iodine
Iodine (Greek: Iodes - purple), is a chemical element in the periodic table that has the symbol I and atomic number 53. This element is required by almost all living things. Iodine is a halogen that reactivity is the lowest and most electropositive. As with all elements of the other halogens, iodine is found in the form of molecules of diatomic.
e. Astatine
A chemical element in the periodic table that has the symbol At and atomic number 85. The name of this element comes from the Greek αστατος (astatos) meaning "unstable." This element is included group halogen and an element of radioactive naturally occurring.
