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Encyclopedia > Halogen
Group 17
Period
2 9
F
3 17
Cl
4 35
Br
5 53
I
6 85
At
7 117
Uus

The halogens or halogen elements are a series of nonmetal elements from Group 17 (old-style: VII or VIIA; Group 7 IUPAC Style) of the periodic table, comprising fluorine, F; chlorine, Cl; bromine, Br; iodine, I; and astatine, At. The undiscovered element 117, temporarily named ununseptium, may also be considered a halogen. Look up halogen in Wiktionary, the free dictionary. ... A periodic table group is a vertical column in the periodic table of the chemical elements. ... The halogens are a chemical series. ... In the periodic table of the elements, a period is a row of the table. ... A period 2 element is one of the chemical elements in the second row (or period) of the periodic table of the elements. ... Distinguished from fluorene and fluorone. ... A period 3 element is one of the chemical elements in the third row (or period) of the periodic table of the elements. ... General Name, symbol, number chlorine, Cl, 17 Chemical series halogens Group, period, block 17, 3, p Appearance yellowish green Standard atomic weight 35. ... A period 4 element is one of the chemical elements in the fourth row (or period) of the periodic table of the elements. ... Bromo redirects here. ... A period 5 element is one of the chemical elements in the fifth row (or period) of the periodic table of the elements. ... For other uses, see Iodine (disambiguation). ... A period 6 element is one of the chemical elements in the sixth row (or period) of the periodic table of the elements, including the Lanthanides. ... General Name, Symbol, Number astatine, At, 85 Chemical series halogens Group, Period, Block 17, 6, p Appearance metallic (presumed) Standard atomic weight (210) g·mol−1 Electron configuration [Xe] 4f14 5d10 6s2 6p5 Electrons per shell 2, 8, 18, 32, 18, 7 Physical properties Phase solid Melting point 575 K... A period 7 element is one of the chemical elements in the seventh row (or period) of the periodic table of the elements. ... General Name, Symbol, Number ununseptium, Uus, 117 Chemical series presumably halogens Group, Period, Block 17, 7, p Appearance unknown, probably dark metallic Standard atomic weight predicted, (310) g·mol−1 Electron configuration perhaps [Rn] 5f14 6d10 7s2 7p5 (guess based on astatine) Electrons per shell 2, 8, 18, 32, 32... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex... Together with the metals and metalloids, a nonmetal is one of three categories of chemical elements as distinguished by ionization and bonding properties. ... The periodic table of the chemical elements A chemical element, or element, is a type of atom that is defined by its atomic number; that is, by the number of protons in its nucleus. ... A periodic table group is a vertical column in the periodic table of the chemical elements. ... IUPAC logo The International Union of Pure and Applied Chemistry (IUPAC) (Pronounced as eye-you-pack) is an international non-governmental organization established in 1919 devoted to the advancement of chemistry. ... The Periodic Table redirects here. ... Distinguished from fluorene and fluorone. ... General Name, symbol, number chlorine, Cl, 17 Chemical series halogens Group, period, block 17, 3, p Appearance yellowish green Standard atomic weight 35. ... Bromo redirects here. ... For other uses, see Iodine (disambiguation). ... General Name, Symbol, Number astatine, At, 85 Chemical series halogens Group, Period, Block 17, 6, p Appearance metallic (presumed) Standard atomic weight (210) g·mol−1 Electron configuration [Xe] 4f14 5d10 6s2 6p5 Electrons per shell 2, 8, 18, 32, 18, 7 Physical properties Phase solid Melting point 575 K... General Name, Symbol, Number ununseptium, Uus, 117 Chemical series presumably halogens Group, Period, Block 17, 7, p Appearance unknown, probably dark metallic Standard atomic weight predicted, (310) g·mol−1 Electron configuration perhaps [Rn] 5f14 6d10 7s2 7p5 (guess based on astatine) Electrons per shell 2, 8, 18, 32, 32...


The group of halogens is the only group which contains elements in all three familiar states of matter at standard temperature and pressure. In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... Temperature and air pressure can vary from one place to another on the Earth, and can also vary in the same place with time. ...

Contents

Abundance

Owing to their high reactivity, the halogens are found in the environment only in compounds or as ions. Halide ions and oxoanions such as IO3 can be found in many minerals and in seawater. Halogenated organic compounds can also be found as natural products in living organisms. In their elemental forms, the halogens exist as diatomic molecules, but these only have a fleeting existence in nature and are much more common in the laboratory and in industry. At room temperature and pressure, fluorine and chlorine are gases, bromine is a liquid and iodine and astatine are solids; Group 17 is therefore the only periodic table group exhibiting all three states of matter at room temperature. Reactivity refers to the rate at which a chemical substance tends to undergo a chemical reaction in time. ... Look up chemical compound in Wiktionary, the free dictionary. ... This article is about the electrically charged particle. ... A halide is a binary compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative than the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound. ... Definition An oxyanion is a polyatomic ion with a negative charge that contains oxygen. ... An iodate is a salt of iodic acid. ... An organic halide is an organic compound containing one or more halogen atoms. ... A space-filling model of the diatomic molecule dinitrogen, N2. ... In the physical sciences, a state of matter is one of the many ways that matter can interact with itself to form a macroscopic, homogenous phase. ...


Etymology

The term halogen originates from 18th century scientific French nomenclature based on erring adaptations of Greek roots; the Greek word halos meaning "salt", and genes meaning "production" — referring to elements which produce a salt in union with a metal. (17th century - 18th century - 19th century - more centuries) As a means of recording the passage of time, the 18th century refers to the century that lasted from 1701 through 1800. ... For other uses, see Salt (disambiguation). ... This article is about metallic materials. ...


Properties

The halogens show a number of trends when moving down the group - for instance, decreasing electronegativity and reactivity, increasing melting and boiling point. Electronegativity is a measure of the ability of an atom or molecule to attract electrons in the context of a chemical bond. ... The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. ... Italic text This article is about the boiling point of liquids. ...

Halogen Standard Atomic Weight (u) Melting Point (K) Boiling Point (K) Electronegativity (Pauling)
Fluorine 18.998 53.53 85.03 3.98
Chlorine 35.453 171.6 239.11 3.16
Bromine 79.904 265.8 332.0 2.96
Iodine 126.904 386.85 457.4 2.66
Astatine (210) 575 610 ? 2.2
Ununseptium (291)* * * *

* Ununseptium has not yet been discovered; values are either unknown if no value appears, or are estimates based on other similar chemicals. The atomic mass unit (amu), unified atomic mass unit (u), or dalton (Da), is a small unit of mass used to express atomic masses and molecular masses. ... For other uses, see Kelvin (disambiguation). ... For other uses, see Kelvin (disambiguation). ... Electronegativity is a measure of the attraction that an atom has for the bonding pair of electrons in a covalent bond. ... Distinguished from fluorene and fluorone. ... General Name, symbol, number chlorine, Cl, 17 Chemical series halogens Group, period, block 17, 3, p Appearance yellowish green Standard atomic weight 35. ... Bromo redirects here. ... For other uses, see Iodine (disambiguation). ... General Name, Symbol, Number astatine, At, 85 Chemical series halogens Group, Period, Block 17, 6, p Appearance metallic (presumed) Standard atomic weight (210) g·mol−1 Electron configuration [Xe] 4f14 5d10 6s2 6p5 Electrons per shell 2, 8, 18, 32, 18, 7 Physical properties Phase solid Melting point 575 K... General Name, Symbol, Number ununseptium, Uus, 117 Chemical series presumably halogens Group, Period, Block 17, 7, p Appearance unknown, probably dark metallic Standard atomic weight predicted, (310) g·mol−1 Electron configuration perhaps [Rn] 5f14 6d10 7s2 7p5 (guess based on astatine) Electrons per shell 2, 8, 18, 32, 32...


Diatomic halogen molecules

halogen molecule structure model d(X−X) / pm
(gas phase)
d(X−X) / pm
(solid phase)
fluorine
F2
143
149
chlorine
Cl2
199
198
bromine
Br2
228
227
iodine
I2
266
272

Image File history File links Difluorine-2D-dimensions. ... Image File history File links Download high-resolution version (1100x862, 234 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Halogen User:Benjah-bmm27/Gallery/Fluorine ... Image File history File links Download high-resolution version (838x560, 10 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Halogen ... Image File history File links Download high-resolution version (1100x756, 130 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Halogen ... Image File history File links Download high-resolution version (964x557, 10 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Halogen ... Image File history File links Download high-resolution version (1100x790, 129 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Halogen ... Image File history File links Diiodine-2D-dimensions. ... Image File history File links Download high-resolution version (1100x771, 95 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Halogen ...

Chemistry

Reactivity

Halogens are highly reactive, and as such can be harmful or lethal to biological organisms in sufficient quantities. This high reactivity is due to their atoms being one electron short of a full outer shell of eight electrons. They can gain this electron by reacting with atoms of other elements. Fluorine is the most reactive element in existence, attacking such inert materials as glass, and forming compounds with the heavier noble gases. It is a corrosive and highly toxic gas. The reactivity of fluorine is such that, if used or stored in laboratory glassware, it can react with glass in the presence of small amounts of water to form SiF4. Thus fluorine must be handled with substances such as Teflon, extremely dry glass, or metals such as copper or steel which form a protective layer of fluoride on their surface. Reactivity refers to the rate at which a chemical substance tends to undergo a chemical reaction in time. ... Life on Earth redirects here. ... Distinguished from fluorene and fluorone. ... The noble gases are a chemical series. ... In chemistry, polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer which finds numerous applications. ...


Both chlorine and bromine are used as disinfectants for drinking water, swimming pools, fresh wounds, dishes, and surfaces. They kill bacteria and other potentially harmful microorganisms through a process known as sterilization. Their reactivity is also put to use in bleaching. Sodium hypochlorite, which is produced from chlorine, is the active ingredient of most fabric bleaches and chlorine-derived bleaches are used in the production of some paper products. Disinfection The destruction of pathogenic and other kinds of microorganisms by physical or chemical means Disinfectants are chemical substances used to kill viruses and microbes (germs), such as bacteria and fungi. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... A microorganism or microbe is an organism that is so small that it is microscopic (invisible to the naked eye). ... Sterilization (or sterilisation) refers to any process that effectively kills or eliminates transmissible agents (such as fungi, bacteria, viruses and prions) from a surface, equipment, foods, medications, or biological culture medium. ... A bleaching agent is any compound that bleaches the colour out of fabrics, paper, or other materials. ... Sodium hypochlorite is a chemical compound with the formula NaClO. Sodium hypochlorite solution, commonly known as bleach, is frequently used as a disinfectant and as a bleaching agent. ... It has been suggested that Textile be merged into this article or section. ... For other uses, see Paper (disambiguation). ...


Hydrogen halides

The halogens all form binary compounds with hydrogen, the hydrogen halides, HX (HF, HCl, HBr, HI), a series of particularly strong acids. When in aqueous solution, the hydrogen halides are known as hydrohalic acids. HAt, or "hydrastatic acid", should also qualify, but it is not typically included in discussions of hydrohalic acid due to astatine's extreme instability toward alpha decay. It has been suggested that this article or section be merged with Hydrohalic acid. ... Hydrogen fluoride is a chemical compound with the formula HF. Together with hydrofluoric acid, it is the principal industrial source of fluorine and hence the precursor to many important compounds including pharmaceuticals and polymers (e. ... R-phrases , S-phrases , , , , Flash point non-flammable Supplementary data page Structure and properties n, εr, etc. ... Flash point Non flammable Supplementary data page Structure and properties n, εr, etc. ... HAHAHAHAHAHAAHAHAHAHAHAHAH YOU SUCK Hydrogen iodide (HI) is a diatomic molecule. ... For other uses, see Acid (disambiguation). ... Hydrohalic acid is a group name for the acids of the halogens, which are the aqueous solutions of the hydrogen halides: Fluorine F - hydrofluoric acid: HF Chlorine Cl - hydrochloric acid: HCl Bromine Br - hydrobromic acid: HBr Iodine I - hydroiodic acid: HI As you move further up the list the acids... Alpha decay Alpha decay is a type of radioactive decay in which an atom emits an alpha particle (two protons and two neutrons bound together into a particle identical to a helium nucleus) and transforms (or decays) into an atom with a mass number 4 less and atomic number 2...


Interhalogen compounds

Main article: Interhalogen

The halogens react with each other to form interhalogen compounds. Diatomic interhalogen compounds (e.g. BrF, ICl, ClF) bear resemblance to the pure halogens in some respects. The properties and behaviour of a diatomic interhalogen compound tend to be intermediate between those of its parent halogens. Some properties, however, are found in neither parent halogen − Cl2 and I2 are soluble in CCl4 but ICl is not, since it is a polar molecule due to the relatively large electronegativity difference between I and Cl. The halogens react with each other to form interhalogen compounds. ... Iodine monochloride is the compound with the formula ICl. ... Chlorine monofluoride has formula ClF. External links National Pollutant Inventory - Flouride and compounds fact sheet WebBook page for ClF Categories: | | ... R-phrases , , , , S-phrases , , , , , Flash point Non flammable Supplementary data page Structure and properties n, εr, etc. ... A commonly-used example of a polar compound is water (H2O). ... Electronegativity is a measure of the ability of an atom or molecule to attract electrons in the context of a chemical bond. ...


Organohalogen compounds

Many synthetic organic compounds such as plastic polymers, and a few natural ones, contain halogen atoms; these are known as halogenated compounds or organic halides. Chlorine is by far the most abundant of the halogens, and the only one needed in relatively large amounts (as chloride ions) by humans. For example, chloride ions play a key role in brain function by mediating the action of the inhibitory transmitter GABA and are also used by the body to produce stomach acid. Iodine is needed in trace amounts for the production of thyroid hormones such as thyroxine. On the other hand, neither fluorine nor bromine are believed to be essential for humans, although small amounts of fluoride can make tooth enamel resistant to decay. An organic compound is any of a large class of chemical compounds whose molecules contain carbon, with exception of carbides, carbonates and carbon oxides. ... For other uses, see Plastic (disambiguation). ... A polymer is a long, repeating chain of atoms, formed through the linkage of many molecules called monomers. ... An organic halide is an organic compound containing one or more halogen atoms. ... The human brain In animals, the brain (enkephalos) (Greek for in the skull), is the control center of the central nervous system, responsible for behavior. ... Gaba may refer to: Gabâ or gabaa (Philippines), the concept of negative karma of the Cebuano people GABA, the gamma-amino-butyric acid neurotransmitter GABA receptor, in biology, receptors with GABA as their endogenous ligand Gaba 1 to 1, an English conversational school in Japan Marianne Gaba, a US model... Thyroxine, or 3:5,3:5 tetra­iodothyronine (often abbreviated as T4) is the major hormone secreted by the follicular cells of the thyroid gland. ...


Drug discovery

In drug discovery, the incorporation of halogen atoms into a lead drug candidate results in analogues that are more lipophilic and less water soluble. Consequently, halogen atoms are used to improve penetration through lipid membranes. However, there is an undesirable tendency for halogenated drugs to accumulate in lipid tissue. In medicine, biotechnology and pharmacology, drug discovery is the process by which drugs are discovered and/or designed. ... This article or section does not cite its references or sources. ... A diagonal molecular slab from the DPPC lipid bilayer simulation1; color scheme: PO4 - green, N(CH3)3 - violet, water - blue, terminal CH3 - yellow, O - red, glycol C - brown, chain C - grey. ...


The chemical reactivity of halogen atoms depends on both their point of attachment to the lead and the nature of the halogen. Aromatic halogen groups are far less reactive than aliphatic halogen groups, which can exhibit considerable chemical reactivity. For aliphatic carbon-halogen bonds the C-F bond is the strongest and usually less chemically reactive than aliphatic C-H bonds. The other aliphatic-halogen bonds are weaker, their reactivity increasing down the periodic table. They are usually more chemically reactive than aliphatic C-H bonds. Consequently, the most popular halogen substitutions are the less reactive aromatic fluorine and chlorine groups. In chemistry, an aromatic molecule is one in which electrons are free to cycle around circular arrangements of atoms, which are alternately singly and doubly bonded to one another. ... In chemistry, non-aromatic and non-cyclic (acyclic) organic compounds are called aliphatic. ...


See also

Pseudohalogens are binary inorganic compounds of the general form XY, where X is a cyanide, cyanate, thiocyanate etc. ... A halogen bond is the noncovalent interaction between a halogen atom (iodine, bromine, chlorine) and an electron rich environment like a lone pair of oxygen or nitrogen. ...

References

  1. N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, 2nd ed., Butterworth-Heinemann, Oxford, UK, 1997.
  2. G. Thomas, Medicinal Chemistry an Introduction, John Wiley & Sons, West Sussex, UK, 2000.
Explanation of above periodic table slice:
Halogens Atomic numbers in red are gases Atomic numbers in green are liquids Atomic numbers in black are solids
Solid borders indicate primordial elements (older than the Earth) Dashed borders indicate radioactive natural elements Dotted borders indicate radioactive synthetic elements No borders indicates undiscovered elements

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