| 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. In Chemistry a group, also known as a family, is a vertical column in the Periodic table of the Chemical elements There are 18 groups in Abundance Owing to their high Reactivity, the halogens are found in the environment only in compounds or as Ions Halide ions and oxoanions In the Periodic table of the elements, a period is a horizontal 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 chemical elements. Fluorine, fluorum meaning "to flow" is the Chemical element with the symbol F and Atomic number 9 A period 3 element is one of the Chemical elements in the third row (or period) of the periodic table of the elements. Chlorine (ˈklɔriːn from the Greek word 'χλωρóς' ( khlôros, meaning 'pale green' is the Chemical element with Atomic number 17 and A period 4 element is one of the Chemical elements in the fourth row (or period) of the periodic table of the elements. A period 5 element is one of the Chemical elements in the fifth row (or period) of the periodic table of the elements. Iodine (ˈaɪədaɪn ˈaɪədɪn or /ˈaɪədiːn/ from ιώδης iodes "violet" is a Chemical element that has the symbol I and Atomic 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 Astatine (ˈæstətiːn is a Radioactive Chemical element with the symbol At and Atomic number 85 A period 7 element is one of the Chemical elements in the seventh row (or period) of the periodic table of the elements. Ununseptium (ˌjuːnənˈsɛptiəm or /ˌʌnənˈsɛptiəm/ is the temporary name of an undiscovered Chemical element in the Periodic table that has the temporary In Chemistry a group, also known as a family, is a vertical column in the Periodic table of the Chemical elements There are 18 groups in Nonmetal is a term used in Chemistry when classifying the Chemical elements On the basis of their general physical and chemical properties every element in the A chemical element is a type of Atom that is distinguished by its Atomic number; that is by the number of Protons in its nucleus. In Chemistry a group, also known as a family, is a vertical column in the Periodic table of the Chemical elements There are 18 groups in The International Union of Pure and Applied Chemistry ( IUPAC) (aɪjuːpæk or ay-yoo-pec) is an international Non-governmental organization The periodic table of the chemical elements is a tabular method of displaying the Chemical elements Although precursors to this table exist its invention is Fluorine, fluorum meaning "to flow" is the Chemical element with the symbol F and Atomic number 9 Chlorine (ˈklɔriːn from the Greek word 'χλωρóς' ( khlôros, meaning 'pale green' is the Chemical element with Atomic number 17 and Iodine (ˈaɪədaɪn ˈaɪədɪn or /ˈaɪədiːn/ from ιώδης iodes "violet" is a Chemical element that has the symbol I and Atomic Astatine (ˈæstətiːn is a Radioactive Chemical element with the symbol At and Atomic number 85 The undiscovered element 117, temporarily named ununseptium, may also be a halogen. Ununseptium (ˌjuːnənˈsɛptiəm or /ˌʌnənˈsɛptiəm/ is the temporary name of an undiscovered Chemical element in the Periodic table that has the temporary
The group of halogens is the only group which contains elements in all three familiar states of matter at standard temperature and pressure. A state of matter (or physical state, or form of matter) has physical properties which are qualitatively different from other states of matter In Physical sciences standard conditions for temperature and pressure are Standard sets of conditions for experimental measurements to allow comparisons to be made
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Abundance
Owing to their high reactivity, the halogens are found in the environment only in compounds or as ions. A chemical compound is a substance consisting of two or more different elements chemically bonded together in a fixed proportion by Mass. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Halide ions and oxoanions such as iodate (IO3−) can be found in many minerals and in seawater. 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 An oxyanion or oxoanion is a negatively charged Polyatomic ion that contains Oxygen. An iodate is a Salt of Iodic acid. In the iodate Anion, Iodine is bonded to three Oxygen atoms and the Molecular formula Halogenated organic compounds can also be found as natural products in living organisms. Halocarbon compounds are Chemicals in which one or more Carbon Atoms are linked by Covalent bonds with one or more Halogen Atoms 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. Diatomic molecules are molecules made only of two Atoms of either the same or different Chemical elements The prefix di- means two in Greek 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. A state of matter (or physical state, or form of matter) has physical properties which are qualitatively different from other states of matter
Etymology
The term halogen originates from 18th century scientific French nomenclature based on adaptations of Greek roots: hals (sea) or halas (salt), and gen- (to generate) — referring to elements which produce a salt in union with a metal. The 18th century lasted from 1701 to 1800 in the Gregorian calendar, in accordance with the Anno Domini / Common Era numbering system This article is about the country For a topic outline on this subject see List of basic France topics. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly A salt, in Chemistry, is defined as the product formed from the neutralisation reaction of Acids and bases. The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across
Properties
The halogens show a number of trends when moving down the group - for instance, decreasing electronegativity and reactivity, and increasing melting and boiling point. " Electronegativity " is the opposite of " Electropositivity," which describes an element's ability to donate electrons The melting point of a solid is the temperature range at which it changes state from solid to Liquid. The boiling point of a liquid is the temperature at which the Vapor pressure of the liquid equals the environmental pressure surrounding the liquid
| Halogen | Standard Atomic Weight (u) | Melting Point (K) | Boiling Point (K) | Electronegativity (Pauling) |
| Fluorine | 18. The unified atomic mass unit ( u) or Dalton ( Da) or sometimes universal mass unit, is an unit of Mass used to express The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic " Electronegativity " is the opposite of " Electropositivity," which describes an element's ability to donate electrons Fluorine, fluorum meaning "to flow" is the Chemical element with the symbol F and Atomic number 9 998 | 53. 53 | 85. 03 | 3. 98 |
| Chlorine | 35. Chlorine (ˈklɔriːn from the Greek word 'χλωρóς' ( khlôros, meaning 'pale green' is the Chemical element with Atomic number 17 and 453 | 171. 6 | 239. 11 | 3. 16 |
| Bromine | 79. 904 | 265. 8 | 332. 0 | 2. 96 |
| Iodine | 126. Iodine (ˈaɪədaɪn ˈaɪədɪn or /ˈaɪədiːn/ from ιώδης iodes "violet" is a Chemical element that has the symbol I and Atomic 904 | 386. 85 | 457. 4 | 2. 66 |
| Astatine | (210) | 575 | 610 ? | 2. Astatine (ˈæstətiːn is a Radioactive Chemical element with the symbol At and Atomic number 85 2 |
Diatomic halogen molecules
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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 the 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 otherwise inert materials such as glass, and forming compounds with the heavier noble gases. Fluorine, fluorum meaning "to flow" is the Chemical element with the symbol F and Atomic number 9 History Noble gas is translated from the German noun de ''Edelgas'' first used in 1898 by Hugo Erdmann to indicate their extremely low level of reactivity 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 silicon tetrafluoride (SiF4). Silicon tetrafluoride or Tetrafluorosilane is the Chemical compound with the formula Si[[Fluorine F]]4 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. In Chemistry, poly(tetrafluoroethene or poly(tetrafluoroethylene ( 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. Disinfectants are Antimicrobial agents that are applied to non-living objects to destroy Microorganisms, the process of which is known as disinfection. They kill bacteria and other potentially harmful microorganisms through a process known as sterilization. The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have A microorganism (also spelled micro organism or micro-organism and also called a microbe) is an Organism that is Microscopic (usually Sterilization (or sterilisation, see spelling differences) refers to any process that effectively kills or eliminates transmissible agents (such as Fungi Their reactivity is also put to use in bleaching. A bleach is a Chemical that removes color or whitens often via Oxidation. 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. Sodium hypochlorite is a Chemical compound with the formula NaClO A textile is a flexible material comprised of a network of natural or artificial Fibres often referred to as thread or Yarn. Paper is thin material mainly used for writing upon printing upon or packaging
Hydrogen halides
The halogens all form binary compounds with hydrogen, the hydrogen halides HF, HCl, HBr, HI, and HAt), a series of particularly strong acids. Hydrogen halides (or hydrohalic acids) are acids resulting from the chemical reaction of Hydrogen with one of the Halogen elements ( Fluorine, Structure HF forms orthorhombic crystals consisting of zig-zag chains of HF molecules Hydrogen bromide is the diatomic molecule H[[Bromine Br]] Under standard conditions HBr is a gas but it can be liquified Hydrogen iodide (HI is a Diatomic molecule. Aqueous solutions of HI are known as hydroiodic acid or hydriodic acid, a Strong acid. In Computer science, ACID ( Atomicity Consistency Isolation Durability) is a set of properties that guarantee that Database transactions are When in aqueous solution, the hydrogen halides are known as hydrohalic acids. Hydrogen halides (or hydrohalic acids) are acids resulting from the chemical reaction of Hydrogen with one of the Halogen elements ( Fluorine, 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. Alpha decay is a type of radioactive decay in which an Atomic nucleus emits an Alpha particle (two protons and two neutrons bound together into a particle
Interhalogen compounds
The halogens react with each other to form interhalogen compounds. The Halogens react with each other to form interhalogen compounds Diatomic interhalogen compounds such as BrF, ICl, and ClF) bear resemblance to the pure halogens in some respects. Iodine monochloride is the Chemical compound with the formula ICl Chlorine monofluoride is a volatile Interhalogen compound with the Chemical formula ClF 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. For example, 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. Carbon tetrachloride, also known by many other names (see Table is the Organic compound with the formula CCl4 "Polar molecule" and "Non-polar" redirect here " Electronegativity " is the opposite of " Electropositivity," which describes an element's ability to donate electrons
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. An organic compound is any member of a large class of Chemical compounds whose Molecules contain Carbon. Plastic is the general common term for a wide range of synthetic or semisynthetic organic solid materials suitable for the manufacture of industrial products A polymer is a large Molecule ( Macromolecule) composed of repeating Structural units typically connected by Covalent Chemical bonds Halocarbon compounds are Chemicals in which one or more Carbon Atoms are linked by Covalent bonds with one or more Halogen Atoms 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. The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain Gamma-aminobutyric acid (GABA is the chief inhibitory Neurotransmitter in the Mammalian Central nervous system. Iodine is needed in trace amounts for the production of thyroid hormones such as thyroxine. The thyroid is one of the largest Endocrine glands in the body Thyroxine, or 353'5'-tetraiodothyronine (often abbreviated as T4) a form of Thyroid hormones is the major Hormone secreted by the 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.
Drug discovery
In drug discovery, the incorporation of halogen atoms into a lead drug candidate results in analogues that are usually more lipophilic and less water soluble. In Medicine, Biotechnology and Pharmacology, drug discovery is the process by which drugs are discovered and/or designed Lipophilicity, fat-liking, refers to the ability of a Chemical compound to dissolve in fats oils lipids and non-polar solvents such as Hexane or [1] Consequently, halogen atoms are used to improve penetration through lipid membranes and tissues. A lipid bilayer or bilayer lipid membrane ( BLM) is a membrane composed of Lipid molecules (usually Phospholipids. Consequently, there is an tendency for some halogenated drugs to accumulate in adipose tissue. "Adipose" redirects here For the Doctor Who monster see " Partners in Crime "
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. In Organic chemistry, compounds composed of Carbon and Hydrogen are divided into two classes Aromatic compounds which contain Benzene rings 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 common halogen substitutions are the less reactive aromatic fluorine and chlorine groups.
Solubility in water
Fluorine reacts vigorously with water to produce oxygen (O2) and hydrogen fluoride (HF):[2]
- 2 F2(g) + 2 H2O(l) → O2(g) + 4 HF(aq)
Chlorine has minimal solubility in water, with maximum solubility at 49. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Structure HF forms orthorhombic crystals consisting of zig-zag chains of HF molecules 3°F (9. 6°C) when approximately 1% is dissolved. [3] Dissolved chlorine reacts to form hydrochloric acid (HCl) and hypochlorous acid, a solution that can be used as a disinfectant or bleach:
- Cl2(g) + H2O(l) → HCl(aq) + HClO(aq)
Bromine has a solubility of 3. Hydrochloric acid is the Solution of Hydrogen chloride ( H[[Chlorine Cl]] in water Hypochlorous acid ( IUPAC name chloric(I acid) is a weak Acid with the Chemical formula HOCl Disinfectants are Antimicrobial agents that are applied to non-living objects to destroy Microorganisms, the process of which is known as disinfection. A bleach is a Chemical that removes color or whitens often via Oxidation. 41 g per 100 g of water,[4] but it slowly reacts to form hydrogen bromide (HBr) and hypobromous acid (HBrO):
- Br2(g) + H2O(l) → HBr(aq) + HBrO(aq)
Iodine, however, is minimally soluble in water (0. Hydrogen bromide is the diatomic molecule H[[Bromine Br]] Under standard conditions HBr is a gas but it can be liquified Hypobromous acid is a weak unstable Acid with Chemical formula HOBr 03 g/100 g water @ 20 °C) and does not react with it. [5]
See also
References
- ^ G. Pseudohalogens are binary Inorganic compounds of the general form XY where X is a Cyanide, Cyanate, Thiocyanate etc A halogen bond is the Noncovalent attractive interaction between an electron poor Halogen atom (usually Iodine or Bromine) and an electron rich Thomas, Medicinal Chemistry an Introduction, John Wiley & Sons, West Sussex, UK, 2000.
- ^ The Oxidising Ability of the Group 7 Elements
- ^ Solubility of chlorine in water
- ^ Properties of bromine
- ^ Iodine MSDS
Further reading
- N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, 2nd ed. , Butterworth-Heinemann, Oxford, UK, 1997.
| 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 |
EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. In chemistry the Chemical elements labeled as synthetic are too unstable to be found naturally on Earth.
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