• The The halogenshalogens are a are a chemical serieschemical series. . They are the They are the elementselements in in Group 17Group 17 (old- (old-style: VII or VIIA) of the style: VII or VIIA) of the periodic tableperiodic table: : fluorinefluorine ( (FF), ), chlorinechlorine ( (ClCl), ), brominebromine ( (BrBr), ), iodineiodine ( (II), ), astatineastatine ( (AtAt) and the as yet ) and the as yet undiscovered undiscovered ununseptiumununseptium ( (UusUus). The ). The term halogen was coined to mean term halogen was coined to mean elements which produce elements which produce saltsalt in union with in union with a a metalmetal. It comes from . It comes from 18th century18th century scientific scientific FrenchFrench nomenclature based on nomenclature based on erring adaptations of erring adaptations of GreekGreek roots. roots.

• These elements are These elements are diatomicdiatomic moleculesmolecules in in their natural form. They require one more their natural form. They require one more electronelectron to fill their outer to fill their outer electron shellselectron shells, , and so have a tendency to form a singly-and so have a tendency to form a singly-charged charged negativenegative ionion. This negative ion is . This negative ion is referred to as a halide ion; referred to as a halide ion; saltssalts containing these ions are known as containing these ions are known as halideshalides..

• Halogens are highly Halogens are highly reactivereactive, and as , and as such can be harmful or lethal to such can be harmful or lethal to biologicalbiological organismsorganisms in sufficient in sufficient quantities. Halide ions combined with quantities. Halide ions combined with single single hydrogenhydrogen atomsatoms form the form the hydrohalic acidshydrohalic acids (i.e., HF, HCl, HBr, (i.e., HF, HCl, HBr, HI), a series of particularly strong HI), a series of particularly strong acidsacids. (HAt, or "hydrastatic acid", . (HAt, or "hydrastatic acid", should also qualify, but it is not should also qualify, but it is not typically included in discussions of typically included in discussions of hydrohalic acid due to astatine's hydrohalic acid due to astatine's extreme instability toward extreme instability toward alpha decayalpha decay.).)

FLOURINEFLOURINE

Atomic Symbol:Atomic Symbol: F FAtomic Number:Atomic Number:99 Atomic Weight:Atomic Weight: 18.998403 18.998403 From the Latin and French words for flow, From the Latin and French words for flow,

fluere. fluere.

History Of DiscoveryHistory Of Discovery• Fluorine in the form of Fluorine in the form of fluorsparfluorspar (also called (also called fluoritefluorite) () (

calcium fluoridecalcium fluoride) was described in ) was described in 15301530 by by Georgius AgricolaGeorgius Agricola for its use as a for its use as a fluxflux [1][1], which is a , which is a substance that is used to promote the fusion of substance that is used to promote the fusion of metalsmetals or or mineralsminerals. In . In 16701670 SchwanhardSchwanhard found that glass was etched found that glass was etched when it was exposed to when it was exposed to fluorsparfluorspar that was treated with that was treated with acidacid. . Karl ScheeleKarl Scheele and many later researchers, including and many later researchers, including Humphry DavyHumphry Davy, , Gay-LussacGay-Lussac, , Antoine LavoisierAntoine Lavoisier, and , and Louis ThenardLouis Thenard all would experiment with hydrofluoric acid, all would experiment with hydrofluoric acid, easily obtained by treating calcium fluoride (easily obtained by treating calcium fluoride (fluorsparfluorspar) with ) with concentrated sulfuric acid.concentrated sulfuric acid.

• It was eventually realized that hydrofluoric acid contained a It was eventually realized that hydrofluoric acid contained a previously unknown element. This element was not isolated previously unknown element. This element was not isolated for many years after this due to its extreme reactivity - it is for many years after this due to its extreme reactivity - it is separated from its compounds only with difficulty and then it separated from its compounds only with difficulty and then it immediately attacks the remaining materials of the immediately attacks the remaining materials of the compound. Finally, in compound. Finally, in 18861886, fluorine was isolated by , fluorine was isolated by Henri MoissanHenri Moissan after almost 74 years of continuous effort. It after almost 74 years of continuous effort. It was an effort which cost several researchers their health or was an effort which cost several researchers their health or even their lives, and for Moissan, it earned him the 1906 even their lives, and for Moissan, it earned him the 1906 Nobel Prize in chemistry.Nobel Prize in chemistry.

• The first large scale production of fluorine The first large scale production of fluorine was needed for the was needed for the atomic bombatomic bomb Manhattan projectManhattan project in in World War IIWorld War II where where the compound the compound uranium hexafluorideuranium hexafluoride (UF6) (UF6) was used to separate the 235U and 238U was used to separate the 235U and 238U isotopesisotopes of of uraniumuranium. Today both the . Today both the gaseous diffusiongaseous diffusion process and the process and the gas centrifugegas centrifuge process use gaseous (UF6) process use gaseous (UF6) to produce to produce enriched uraniumenriched uranium for for nuclear powernuclear power applications. applications.

• The derivation of elemental fluorine from The derivation of elemental fluorine from hydrofluoric acid is exceptionally hydrofluoric acid is exceptionally dangerous, killing or blinding several dangerous, killing or blinding several scientists who attempted early experiments scientists who attempted early experiments on this halogen. These men came to be on this halogen. These men came to be referred to as "Fluorine Martyrs."referred to as "Fluorine Martyrs."

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General DescriptionGeneral Description

• Fluorine is the most electronegative and reactive of all Fluorine is the most electronegative and reactive of all elements. It is a pale yellow, corrosive gas, which reacts with elements. It is a pale yellow, corrosive gas, which reacts with most organic and inorganic substances. Finely divided metals, most organic and inorganic substances. Finely divided metals, glass, ceramics, carbon, and even water burn in fluorine with a glass, ceramics, carbon, and even water burn in fluorine with a bright flame. bright flame.

• Flourine is so dangerous that it must be stored in steel Flourine is so dangerous that it must be stored in steel containers, and even then it reacts with the steel. Fortunately containers, and even then it reacts with the steel. Fortunately the layer of flouride that is formed is unreactive, and prevents the layer of flouride that is formed is unreactive, and prevents it from reacting further. it from reacting further.

• Flourine is the most reactive element in the world. It reacts Flourine is the most reactive element in the world. It reacts with absolutely with absolutely everything everything (except for nitrogen, oxygen and (except for nitrogen, oxygen and some of the lighter noble gases), very often explosively. some of the lighter noble gases), very often explosively.

• Flourine attacks and breaks down most organic compounds Flourine attacks and breaks down most organic compounds which burn in it's pale yellow gas. which burn in it's pale yellow gas.

..

Chemical PropertiesChemical Properties

• Electrochemical EquivalentElectrochemical Equivalent:: 0.70883g/amp-hr 0.70883g/amp-hr • Electron Work Function:Electron Work Function: • Electronegativity (Pauling):Electronegativity (Pauling): 3.98 3.98 • Heat of Fusion:Heat of Fusion: 0.2552kJ/mol 0.2552kJ/mol • Incompatiblities:Incompatiblities: • Water, nitric acid, oxidizers, organic compoundsWater, nitric acid, oxidizers, organic compounds• Ionization PotentialIonization Potential • First:First: 17.422 17.422

SecondSecond:: 34.97 34.97ThirdThird:: 62.707 62.707

• valence Electron Potential (-eV):valence Electron Potential (-eV): -10.1 -10.1

Physical PropertiesPhysical Properties• Atomic Mass AverageAtomic Mass Average:: 18.9984 18.9984 • Boiling Point:Boiling Point: 85.10 85.10KK -188.05° -188.05°CC -306.49° -306.49°FF • Coefficient of Linear Thermal Expansion:Coefficient of Linear Thermal Expansion: • ConductivityConductivity • Electrical:Electrical:

Thermal:Thermal: 0.000279 W/cmK 0.000279 W/cmK• Density:Density: 1.696g/L @ 273K & 1atm 1.696g/L @ 273K & 1atm • Enthalpy of Atomization:Enthalpy of Atomization: 79.08 kJ/mole @ 25°C 79.08 kJ/mole @ 25°C • Enthalpy of Fusion:Enthalpy of Fusion: 0.26 kJ/mole 0.26 kJ/mole • Enthalpy of Vaporization:Enthalpy of Vaporization: 3.31 kJ/mole 3.31 kJ/mole • Flammablity Class:Flammablity Class: Non-flammable gas (extreme Non-flammable gas (extreme

oxidizer) oxidizer) • Freezing Point:Freezing Point: see melting pointsee melting point • Heat of Vaporization:Heat of Vaporization: 3.2698kJ/mol 3.2698kJ/mol • Melting Point:Melting Point: 53.63 53.63KK -219.52° -219.52°CC -363.14° -363.14°FF • Molar Volume:Molar Volume: 17.1 cm3/mole 17.1 cm3/mole • Optical Refractive Index:Optical Refractive Index: 1.000195 1.000195 • Specific Heat:Specific Heat: 0.82J/gK 0.82J/gK

Uses and ImportanceUses and Importance• Flourine in the form of flourochloro hydrcarbons Flourine in the form of flourochloro hydrcarbons

are widely used in air conditioning and are widely used in air conditioning and refrigeration, refrigeration,

• Fluorine and its compounds are used in creating Fluorine and its compounds are used in creating isotopically fractionated uranium. isotopically fractionated uranium.

• Commercial fluorochemicals, used for creating Commercial fluorochemicals, used for creating high temperature plastics. high temperature plastics.

• Hydrofluoric acid is often used during etching of Hydrofluoric acid is often used during etching of glass for light bulbs and similar products. glass for light bulbs and similar products.

• Flouride is often included in water or tooth paste Flouride is often included in water or tooth paste to assist in the fight again tooth decay, however not to assist in the fight again tooth decay, however not all countries through the world include Flouride in all countries through the world include Flouride in their water supplies. their water supplies.

• Flourine is used as hydroflouric acid in Flourine is used as hydroflouric acid in aluminium smelting and steel production, and aluminium smelting and steel production, and Cryolite (a naturally accuring Flourine source) is Cryolite (a naturally accuring Flourine source) is used in Aluminium manufacture. Silicoflouride used in Aluminium manufacture. Silicoflouride salts are used mainly in water flouridation and salts are used mainly in water flouridation and laundry detergents. laundry detergents.

• In much higher concentrations, In much higher concentrations, sodium fluoridesodium fluoride has been used as an insecticide, especially has been used as an insecticide, especially against cockroaches. against cockroaches.

• Without flourine, you'd have no recyclable cans, Without flourine, you'd have no recyclable cans, no cars chassis', your clothes would be filthy, no cars chassis', your clothes would be filthy, and water wouldn't be safe to drink. and water wouldn't be safe to drink.

Other FactsOther Facts• Both fluorine and HF must be handled with great care and Both fluorine and HF must be handled with great care and

any contact with any contact with skinskin and and eyeseyes should be strictly avoided. should be strictly avoided. All equipment must be All equipment must be passivatedpassivated before exposure to before exposure to fluorine.fluorine.

• Contact with exposed skin may result in the HF molecule Contact with exposed skin may result in the HF molecule rapidly migrating through the skin and flesh into the bone rapidly migrating through the skin and flesh into the bone where it reacts with calcium permanently damaging the where it reacts with calcium permanently damaging the bone, followed by cardiac arrest brought on by sudden bone, followed by cardiac arrest brought on by sudden chemical changes within the body.chemical changes within the body.

• Both elemental fluorine and fluoride ions are highly toxic. Both elemental fluorine and fluoride ions are highly toxic. When it is a free element, fluorine has a characteristic When it is a free element, fluorine has a characteristic pungent odor that is detectable in concentrations as low as pungent odor that is detectable in concentrations as low as 20 nL/L. It is recommended that the maximum allowable 20 nL/L. It is recommended that the maximum allowable concentration for a daily 8-hour time-weighted exposure is concentration for a daily 8-hour time-weighted exposure is 1 µL/L (1 µL/L (part per million by volumepart per million by volume) (lower than, for ) (lower than, for example, example, hydrogen cyanidehydrogen cyanide).).

Atomic StructureAtomic Structure

• Number Number of Energy of Energy Levels:Levels: 2 2

• First First Energy Energy Level:Level: 2 2

• Second Second Energy Energy Level:Level: 7 7

ChlorineChlorine

• Symbol: Symbol: ClCl• Atomic number: 17Atomic number: 17• from the Greek language from the Greek language chloroschloros, ,

meaning "pale green"meaning "pale green"

History of DiscoveryHistory of Discovery

• Chlorine was discovered in Chlorine was discovered in 17741774 by by Swedish chemist Swedish chemist Carl Wilhelm ScheeleCarl Wilhelm Scheele, , who called it who called it dephlogisticated marine aciddephlogisticated marine acid (see (see Phlogiston theoryPhlogiston theory) and mistakenly ) and mistakenly thought it contained thought it contained oxygenoxygen. Chlorine was . Chlorine was given its current name in given its current name in 18101810 by by Sir Humphry DavySir Humphry Davy, who insisted that it was , who insisted that it was in fact an element.in fact an element.

• Chlorine gas, also known as Chlorine gas, also known as bertholitebertholite, , was first was first used as a weaponused as a weapon against human against human beings in beings in WWIWWI on on April 22ndApril 22nd, , 19151915, and , and afterwards was used by both sides.afterwards was used by both sides.

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General Description General Description • Chlorine is a greenish yellow gas which combines Chlorine is a greenish yellow gas which combines

directly with nearly all elements. Chlorine is a directly with nearly all elements. Chlorine is a respiratory irritant. The gas irritates the mucous respiratory irritant. The gas irritates the mucous membranes and the liquid burns the skin. As little as membranes and the liquid burns the skin. As little as 3.5 ppm can be detected as an odor, and 1000 ppm is 3.5 ppm can be detected as an odor, and 1000 ppm is likely to be fatal after a few deep breaths. It was likely to be fatal after a few deep breaths. It was used as a war gas in 1915. It is not found in a free used as a war gas in 1915. It is not found in a free state in nature, but is found commonly as NaCl (solid state in nature, but is found commonly as NaCl (solid or seawater).or seawater).

• Chlorine, Cl2, reacts with water to produce Chlorine, Cl2, reacts with water to produce hypochlorite, OCl-. The position of the equilibrium hypochlorite, OCl-. The position of the equilibrium depends very much upon the pH of the solution.depends very much upon the pH of the solution.

• This element is a member of the This element is a member of the saltsalt-forming -forming halogen series and is extracted from chlorides halogen series and is extracted from chlorides through through oxidationoxidation and more commonly, by and more commonly, by electrolysiselectrolysis..

• As the chloride ion, Cl-, it is also the most abundant As the chloride ion, Cl-, it is also the most abundant dissolved species in dissolved species in oceanocean water. water.

• As the As the chloridechloride ion, which is part of ion, which is part of common saltcommon salt and other compounds, and other compounds, it is abundant in nature and it is abundant in nature and necessary to most forms of life, necessary to most forms of life, including including humanshumans. As chlorine gas, it . As chlorine gas, it is is greenishgreenish yellowyellow, is two and one , is two and one half times as heavy as air, has an half times as heavy as air, has an intensely disagreeable suffocating intensely disagreeable suffocating odor, and is exceedingly odor, and is exceedingly poisonouspoisonous. . In its liquid and solid form it is a In its liquid and solid form it is a powerful powerful oxidizingoxidizing, , bleachingbleaching, and , and disinfecting agent.disinfecting agent.

Chemical PropertiesChemical Properties• Electrochemical EquivalentElectrochemical Equivalent:: 1.3228g/amp-hr 1.3228g/amp-hr • Electron Work Function:Electron Work Function: • Electronegativity (Pauling):Electronegativity (Pauling): 3.16 3.16 • Heat of Fusion:Heat of Fusion: 3.203kJ/mol 3.203kJ/mol • Incompatiblities:Incompatiblities: • Reacts explosively or forms explosive compounds with Reacts explosively or forms explosive compounds with

many common substances such as acetylene, ether, many common substances such as acetylene, ether, turpentine, ammonia, fuel gas, hydrogen & finely divided turpentine, ammonia, fuel gas, hydrogen & finely divided metals.metals.

• Ionization PotentialIonization Potential • First:First: 12.967 12.967

SecondSecond:: 23.81 23.81ThirdThird:: 39.611 39.611

• valence Electron Potential (-eV):valence Electron Potential (-eV): -7.96 -7.96

Physical PropertiesPhysical Properties• Atomic Mass AverageAtomic Mass Average:: 35.4527 35.4527 • Boiling Point:Boiling Point: 239.3 239.3KK -33.9° -33.9°CC -29° -29°FF • Coefficient of Linear Thermal Expansion:Coefficient of Linear Thermal Expansion: • ConductivityConductivity • Electrical:Electrical:

Thermal:Thermal: 0.000089 W/cmK 0.000089 W/cmK• Density:Density: 3.214g/L @ 273K & 1atm 3.214g/L @ 273K & 1atm • Elastic Modulus:Elastic Modulus: • Bulk:Bulk: 1.1/GPa 1.1/GPa• Enthalpy of Atomization:Enthalpy of Atomization: 121.8 kJ/mole @ 25°C 121.8 kJ/mole @ 25°C • Enthalpy of Fusion:Enthalpy of Fusion: 3.38 kJ/mole 3.38 kJ/mole • Enthalpy of Vaporization:Enthalpy of Vaporization: 10.21 kJ/mole 10.21 kJ/mole • Flammablity Class:Flammablity Class: Non-flammable gas (strong oxidizer) Non-flammable gas (strong oxidizer) • Freezing Point:Freezing Point: see melting pointsee melting point • Heat of Vaporization:Heat of Vaporization: 10.2kJ/mol 10.2kJ/mol • Melting Point:Melting Point: 172.31 172.31KK -100.84° -100.84°CC -149.51° -149.51°FF • Molar Volume:Molar Volume: 18.7 cm3/mole 18.7 cm3/mole • Optical Refractive Index:Optical Refractive Index: 1.000773 1.000773 • Specific Heat:Specific Heat: 0.48J/gK 0.48J/gK • Vapor PressureVapor Pressure = 1300kPa = 1300kPa

Uses and ImportanceUses and Importance• Chlorine became the first killing agent to be Chlorine became the first killing agent to be

employed during employed during World War IWorld War I. German chemical . German chemical conglomerate conglomerate IG FarbenIG Farben had been producing had been producing chlorine as a by-product of their chlorine as a by-product of their dyedye manufacturing. In cooperation with manufacturing. In cooperation with Fritz HaberFritz Haber of of the the Kaiser Wilhelm InstituteKaiser Wilhelm Institute for Chemistry in for Chemistry in BerlinBerlin, they began developing methods of discharging , they began developing methods of discharging chlorine gas against enemy chlorine gas against enemy trenchestrenches..

• Chlorine is commonly used as an antiseptic and is Chlorine is commonly used as an antiseptic and is used to make drinking water safe and to treat used to make drinking water safe and to treat swimming pools. swimming pools.

• Large amounts of chlorine are used in many Large amounts of chlorine are used in many industrial processes, such as in the production of industrial processes, such as in the production of paper products, plastics, dyes, textiles, medicines, paper products, plastics, dyes, textiles, medicines, antiseptics, insecticides, solvents and paints.antiseptics, insecticides, solvents and paints.

Other FactsOther Facts

• Chlorine irritates respiratory systems Chlorine irritates respiratory systems especially in children and the elderly. In especially in children and the elderly. In its gaseous state it irritates its gaseous state it irritates mucous membranesmucous membranes and in its liquid and in its liquid state it burns state it burns skinskin. It takes as little as . It takes as little as 3.5 3.5 ppmppm to be detected as a distinct to be detected as a distinct odor, but it takes 1000 ppm or more to odor, but it takes 1000 ppm or more to be fatal. Because of this, chlorine was be fatal. Because of this, chlorine was one of the gases used during one of the gases used during World War IWorld War I as a as a war gaswar gas

• Number of Number of Energy Energy Levels:Levels: 3 3

• FFirst Energy irst Energy Level:Level: 2 2

• Second Second Energy Energy Level:Level: 8 8

• Third Third Energy Energy Level:Level: 77

BromineBromine

SymbolSymbol: Br: BrAtomic Number:35Atomic Number:35 from Greek word Bromos meaning from Greek word Bromos meaning

"stench""stench"

History of discoveryHistory of discovery

Bromine was discovered by Antoine J. Bromine was discovered by Antoine J. Balard in France in 1826.Balard in France in 1826.

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General descriptionGeneral description Bromine is a Bromine is a chemical elementchemical element in the in the

periodic tableperiodic table that has the symbol Br and that has the symbol Br and atomic numberatomic number 35. A 35. A halogenhalogen element, element, bromine is a red bromine is a red volatilevolatile liquid at standard liquid at standard room temperature which has reactivity room temperature which has reactivity between between chlorinechlorine and and iodineiodine. This element . This element is is corrosivecorrosive to human to human tissuetissue in a liquid in a liquid state and its vapors irritate eyes and state and its vapors irritate eyes and throat. Bromine vapors are very throat. Bromine vapors are very toxictoxic upon upon inhalation.inhalation.

Bromine is the only nonmetallic liquid Bromine is the only nonmetallic liquid element. It is a heavy, mobile, reddish-element. It is a heavy, mobile, reddish-brown liquid, volatilizing readily at room brown liquid, volatilizing readily at room temperature to a red vapor with a strong temperature to a red vapor with a strong disagreeable odor, resembling chlorine, disagreeable odor, resembling chlorine, and having a very irritating effect on the and having a very irritating effect on the eyes and throat; it is readily soluble in eyes and throat; it is readily soluble in water or carbon disulfide, forming a red water or carbon disulfide, forming a red solution, is less active than chlorine but solution, is less active than chlorine but more so than iodine; it unites readily with more so than iodine; it unites readily with many elements and has a bleaching many elements and has a bleaching action; when spilled on the skin it action; when spilled on the skin it produces painful sores. It presents a produces painful sores. It presents a serious health hazard, and maximum serious health hazard, and maximum safety precautions should be taken when safety precautions should be taken when handling it.handling it.

Chemical properties: Chemical properties:

Atomic number: 35Atomic number: 35

Atomic mass: 79.904 g.mol-1Atomic mass: 79.904 g.mol-1

Density: 3.1 g.cm-3 at 20°CDensity: 3.1 g.cm-3 at 20°C

Melting point: -7.2°CMelting point: -7.2°C

Boiling point: 58.8°CBoiling point: 58.8°C

Physical propertiesPhysical properties

Atomic Mass Average: 79.904 Boiling Point: 332.40K 59.25°C 138.65°F Coefficient of Linear Thermal Expansion: Conductivity Electrical: Thermal: 0.00122 W/cmKDensity: 3.119g/cc @ 300K Elastic Modulus: Bulk: 1.9/GPaEnthalpy of Atomization: 111.7 kJ/mole @ 25°C

Enthalpy of Fusion: 5.29 kJ/mole Enthalpy of Vaporization: 15.46 kJ/mole Flammablity Class: Noncombustible Liquid Freezing Point: see melting point Heat of Vaporization: 15.438kJ/mol Melting Point: 266.1K -7.1°C 19.2°F Molar Volume: 25.62 cm3/mole Optical Refractive Index: 1.001132 Pysical State (at 20°C & 1atm): Liquid Realitive Gas Density (Air=1) = 5.51 Specific Heat: 0.473J/gK Vapor Pressure = 5800Pa@-7.1°C

Uses and importance:Uses and importance:

Gasoline antiknock mixturesGasoline antiknock mixtures

FumigantsFumigants

PoisonsPoisons

DyesDyes

Photographic chemicalsPhotographic chemicals

MedicinalMedicinal

Brominated vegetable oilBrominated vegetable oil

Atomic StructureAtomic StructureNumber of Number of Energy Levels:Energy Levels: 4 4 FFirst Energy irst Energy Level:Level: 2 2 Second Energy Second Energy Level:Level: 8 8

Third Energy Third Energy Level:Level: 18 18

Fourth Energy Fourth Energy Level:Level: 7 7

SymbolSymbol: : IIAtomic Number: 53Atomic Number: 53 From the Greek word "iodes" meaning From the Greek word "iodes" meaning

"violet"."violet".

IODINEIODINE

History Of Discovery Iodine was discovered by Barnard Courtois in

1811. He was the son of a manufacturer of saltpeter (potassium nitrate, a vital part of gunpowder). At the time France was at war and gunpowder was in great demand. Saltpeter was isolated from seaweed washed up on the coasts of Normandy and Brittany. To isolate the potassium nitrate, seaweed was burned and the ash then washed with water. The remaining waste was destroyed by adding sulfuric acid. One day Courtois added too much sulfuric acid and a cloud of purple vapor rose. Courtois noted that the vapor crystallized on cold surfaces making dark crystals. Courtois suspected that this was a new element but lacked the money to pursue his observations.

Charles Bernard DesormesCharles Bernard Desormes (1777 - 1862) and (1777 - 1862) and Nicolas ClémentNicolas Clément (1779 - 1841) to continue research. He also (1779 - 1841) to continue research. He also gave some of the substance to gave some of the substance to Joseph Louis Gay-LussacJoseph Louis Gay-Lussac (1778 - 1850), a well-known chemist at that time, and to (1778 - 1850), a well-known chemist at that time, and to André-Marie AmpèreAndré-Marie Ampère (1775 - 1836). On (1775 - 1836). On 29 November29 November 18131813 Dersormes and Clément made public Courtois’ discovery. Dersormes and Clément made public Courtois’ discovery. They described the substance to a meeting of the They described the substance to a meeting of the Imperial Institute of FranceImperial Institute of France. On December 6 Gay-Lussac . On December 6 Gay-Lussac announced that the new substance was either an element announced that the new substance was either an element or a compound of oxygen. Ampère had given some of his or a compound of oxygen. Ampère had given some of his sample to sample to Humphry DavyHumphry Davy (1778 - 1829). Davy did some (1778 - 1829). Davy did some experiments on the substance and noted its similarity to experiments on the substance and noted its similarity to chlorinechlorine. Davy sent a letter dated December 10 to the . Davy sent a letter dated December 10 to the Royal Society of LondonRoyal Society of London stating that he had identified a new stating that he had identified a new element. A large argument erupted between Davy and Gay-element. A large argument erupted between Davy and Gay-Lussac over who identified iodine first but both scientists Lussac over who identified iodine first but both scientists acknowledged Barnard Courtois as the first to isolate the acknowledged Barnard Courtois as the first to isolate the chemical element.chemical element.

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General Description OF ElementGeneral Description OF Element

Iodine is a dark-gray/purple-black solid that Iodine is a dark-gray/purple-black solid that sublimessublimes at standard temperatures into a purple- at standard temperatures into a purple-pink gas that has an irritating odor. This halogen pink gas that has an irritating odor. This halogen forms compounds with many elements, but is forms compounds with many elements, but is less active than the other members of its Group less active than the other members of its Group VII (halogens) and has some metallic-like VII (halogens) and has some metallic-like properties. Iodine dissolves easily in properties. Iodine dissolves easily in chloroformchloroform, , carbon tetrachloridecarbon tetrachloride, or carbon disulphide to , or carbon disulphide to form purple solutions (It is only slightly form purple solutions (It is only slightly solublesoluble in in water, giving a yellow solution). The deep blue water, giving a yellow solution). The deep blue color of color of starchstarch-iodine complexes is produced -iodine complexes is produced only by the free element.only by the free element.

Iodine is a solid diatomic non-metal that is very Iodine is a solid diatomic non-metal that is very pungent in odor and a corrosive poison.pungent in odor and a corrosive poison.Th density of iodine is 4.94 g/mL, which means it Th density of iodine is 4.94 g/mL, which means it will sink in water.will sink in water.

Iodine, I2 is not reactive towards with oxygen, Iodine, I2 is not reactive towards with oxygen, O2, or nitrogen, N2.O2, or nitrogen, N2.

Iodine, I2, reacts with water to produce Iodine, I2, reacts with water to produce hypoiodite, OI-. The position of the equilibrium hypoiodite, OI-. The position of the equilibrium depends very much upon the pH of the solution.depends very much upon the pH of the solution.

In the graphic on the left, iodine element reacts In the graphic on the left, iodine element reacts with zinc metal to form zinc iodide. The reaction with zinc metal to form zinc iodide. The reaction is so exothermic that part of the iodine element is so exothermic that part of the iodine element solid is vaporized to iodine violet gas.solid is vaporized to iodine violet gas.

Chemical Properties:Chemical Properties:

Electrochemical EquivalentElectrochemical Equivalent: 4.7348g/amp-hr : 4.7348g/amp-hr Electron Work Function: Electron Work Function: Electronegativity (Pauling): 2.66 Electronegativity (Pauling): 2.66 Heat of Fusion: 7.824kJ/mol Heat of Fusion: 7.824kJ/mol Incompatiblities: Incompatiblities: Ammonia, acetylene, acetaldehyde, powdered Ammonia, acetylene, acetaldehyde, powdered

aluminum, active metals, liquid chlorinealuminum, active metals, liquid chlorine Ionization Potential Ionization Potential First: 10.451First: 10.451

SecondSecond: 19.131: 19.131ThirdThird: 33: 33

valence Electron Potential (-eV): -6.55valence Electron Potential (-eV): -6.55

Physical Properties:Physical Properties:Atomic Mass AverageAtomic Mass Average:: 126.9045 126.9045 Boiling Point:Boiling Point: 458.6 458.6KK 185.4° 185.4°CC 365.7° 365.7°FF Coefficient of Linear Thermal Coefficient of Linear Thermal

Expansion:Expansion: 0.000093cm/cm/°0.000093cm/cm/°CC (0° (0°CC))ConductivityConductivity Electrical:Electrical: 8.0E -16 106/cm 8.0E -16 106/cm

Thermal:Thermal: 0.00449 W/cmK 0.00449 W/cmKDensity:Density: 4.93g/cc @ 300K 4.93g/cc @ 300K Elastic Modulus:Elastic Modulus: Bulk:Bulk: 7.7/GPa 7.7/GPa

Enthalpy of Atomization:Enthalpy of Atomization: 106.7 kJ/mole @ 106.7 kJ/mole @ 25°C 25°C

Enthalpy of Fusion:Enthalpy of Fusion: 7.76 kJ/mole 7.76 kJ/mole Enthalpy of Vaporization:Enthalpy of Vaporization: 20.88 kJ/mole 20.88 kJ/mole Flammablity Class:Flammablity Class: Non-combustible solid Non-combustible solid Freezing Point:Freezing Point: see melting pointsee melting point Heat of Vaporization:Heat of Vaporization: 20.752kJ/mol 20.752kJ/mol Melting Point:Melting Point: 386.7 386.7KK 113.5° 113.5°CC 236.3° 236.3°FF Molar Volume:Molar Volume: 25.74 cm3/mole 25.74 cm3/mole Pysical State (at 20°C & 1atm):Pysical State (at 20°C & 1atm): Solid Solid Specific Heat:Specific Heat: 0.214J/gK 0.214J/gK

Use and ImportanceUse and Importance In areas where there is little iodine in the diet—typically In areas where there is little iodine in the diet—typically

remote inland areas and semi-arid equatorial climates remote inland areas and semi-arid equatorial climates where no marine foods are eaten—where no marine foods are eaten—iodine deficiencyiodine deficiency gives rise to gives rise to goitergoiter, so called , so called endemic goiterendemic goiter..

In some such areas, this is now combatted by the In some such areas, this is now combatted by the addition of small amounts of iodine to table salt in form of addition of small amounts of iodine to table salt in form of sodium iodide, potassium iodide, potassium iodate—this sodium iodide, potassium iodide, potassium iodate—this product is known as product is known as iodized saltiodized salt..

Iodine compounds have also been added to other Iodine compounds have also been added to other foodstuffs, such as flour, in areas of deficiency. foodstuffs, such as flour, in areas of deficiency.

Iodine deficiency is the leading cause of preventable Iodine deficiency is the leading cause of preventable mental retardationmental retardation. This is caused by lack of thyroid . This is caused by lack of thyroid hormone in the infant. Iodine deficiency remains a hormone in the infant. Iodine deficiency remains a serious problem that affects people around the globe. serious problem that affects people around the globe.

Uncombined (elemental) iodine is mildly Uncombined (elemental) iodine is mildly toxic to all living things. toxic to all living things.

iodide, and thyroxin which contains iodine, iodide, and thyroxin which contains iodine, are used internally in medicine. are used internally in medicine.

A solution of KI and iodine in alcohol is A solution of KI and iodine in alcohol is used as a disinfectant for external wounds. used as a disinfectant for external wounds.

Silver iodide is used in photography Silver iodide is used in photography added to table salt for nutrition to stop added to table salt for nutrition to stop

goiter in the thyroidgoiter in the thyroiddeep blue color in a starch solution is a deep blue color in a starch solution is a

sign of the free elementsign of the free element Iodine is primarily used in Iodine is primarily used in medicinemedicine, ,

photographyphotography and in dyes. and in dyes.

Other FactsOther Facts Direct contact with skin can cause lesions, so it should Direct contact with skin can cause lesions, so it should

be handled with care. Iodine vapor is very irritating to the be handled with care. Iodine vapor is very irritating to the eyeeye and to mucous membranes. Concentration of iodine and to mucous membranes. Concentration of iodine in the air should not exceed 1 in the air should not exceed 1 mgmg//m³m³ (eight-hour time- (eight-hour time-weighted average). When mixed with weighted average). When mixed with ammoniaammonia, it can , it can form form nitrogen triiodidenitrogen triiodide which is extremely sensitive and which is extremely sensitive and can explode unexpectedly.can explode unexpectedly.

The United States The United States Food and Drug AdministrationFood and Drug Administration recommends (recommends (21 CFR21 CFR 101.9 (c)(8)(iv)) 150 101.9 (c)(8)(iv)) 150 microgramsmicrograms of iodine per day for both men and women. Natural of iodine per day for both men and women. Natural sources of iodine include seaweed, such as kelp and sources of iodine include seaweed, such as kelp and seafood. Salt for human consumption is oftenseafood. Salt for human consumption is often

Atomic StructureAtomic Structure Number of Energy Number of Energy

Levels:Levels: 5 5

First Energy Level:First Energy Level: 2 2

Second Energy Second Energy Level:Level: 8 8

Third Energy Third Energy Level:Level: 18 18

Fourth Energy Fourth Energy Level:Level: 18 18

Fifth Energy Level:Fifth Energy Level: 7 7

AstatineAstatineSYMBOL: AtSYMBOL: AtAtomic number: 85.Atomic number: 85. Astatine (after Astatine (after GreekGreek αστατος αστατος astatosastatos, ,

meaning "unsteady")meaning "unsteady")

History of DiscoveryHistory of Discovery

The existence of "eka-iodine" had been The existence of "eka-iodine" had been predicted by predicted by MendeleevMendeleev. Astatine was first . Astatine was first synthesized in synthesized in 19401940 by by Dale R. CorsonDale R. Corson, , K. R. MacKenzieK. R. MacKenzie, and , and Emilio SegrèEmilio Segrè at the at the University of California, BerkeleyUniversity of California, Berkeley by by barraging barraging bismuthbismuth with with alpha particlesalpha particles. An . An earlier name for the element was earlier name for the element was alabaminealabamine (Ab). (Ab).

PICTUREPICTURE

General Description of DiscoveryGeneral Description of Discovery Astatine has the most metallic-like Astatine has the most metallic-like

properties of any of the halogens.properties of any of the halogens. Astatine is irritating to element collectors. Astatine is irritating to element collectors.

Collecting all the man-made elements is of Collecting all the man-made elements is of course impossible, since there are an course impossible, since there are an open-ended number of them of open-ended number of them of increasingly short half-life. So people like increasingly short half-life. So people like to define a "complete" element collection to define a "complete" element collection as one containing all the elements up to as one containing all the elements up to uranium. uranium.

Chemical PropertiesChemical Properties

Electrochemical EquivalentElectrochemical Equivalent:: 7.8346g/amp-hr 7.8346g/amp-hr Electron Work Function:Electron Work Function: Electronegativity (Pauling):Electronegativity (Pauling): 2.2 2.2 Heat of Fusion:Heat of Fusion: 114kJ/mol 114kJ/mol Incompatiblities:Incompatiblities: Ionization PotentialIonization Potential First:First: 9.65 9.65 valence Electron Potential (-eV):valence Electron Potential (-eV):

Physical PropertiesPhysical Properties Atomic Mass AverageAtomic Mass Average:: 210 210 Boiling Point:Boiling Point: 610 610KK 337° 337°CC 639°F 639°F Coefficient of Linear Thermal Expansion:Coefficient of Linear Thermal Expansion: ConductivityConductivity Electrical:Electrical:

Thermal:Thermal: 0.017 W/cmK 0.017 W/cmK Enthalpy of Atomization:Enthalpy of Atomization: 92 kJ/mole @ 25°C 92 kJ/mole @ 25°C Flammablity Class:Flammablity Class: Freezing Point:Freezing Point: see melting pointsee melting point Heat of Vaporization:Heat of Vaporization: kJ/mol kJ/mol Melting Point:Melting Point: 575K 302°C 576°F 575K 302°C 576°F Pysical State (at 20°C & 1atm):Pysical State (at 20°C & 1atm): Solid Solid

Use and ImportanceUse and Importance

Astatine is produced by bombarding Astatine is produced by bombarding bismuth with energetic alpha particles to bismuth with energetic alpha particles to obtain relatively long-lived 209At - 211At, obtain relatively long-lived 209At - 211At, which can then be which can then be distilleddistilled from the target from the target by heating in the presence of air.by heating in the presence of air.

Other FactsOther Facts

Astatine is highly carcinogenic: Mammary Astatine is highly carcinogenic: Mammary and pituitary tumors have been induced in and pituitary tumors have been induced in laboratory animals by a single injection. laboratory animals by a single injection.

Astatine can be produced by bombarding Astatine can be produced by bombarding bismuth with energetic alpha particles to bismuth with energetic alpha particles to obtain the relatively long-lived 209-211At, obtain the relatively long-lived 209-211At, which can be distilled from the target by which can be distilled from the target by heating in air. heating in air.

Atomic StructureAtomic Structure Number of Energy Number of Energy

Levels:Levels: 6 6 First Energy Level:First Energy Level:

2 2

Second Energy Second Energy Level:Level: 8 8

Third Energy Third Energy Level:Level: 18 18

Fourth Energy Fourth Energy Level:Level: 32 32

Fifth Energy Level:Fifth Energy Level: 18 18

Sixth Energy Sixth Energy Level:Level: 7 7