chapter 4d group 17 elements

8/8/2019 Chapter 4d Group 17 Elements

1/14

Group 17 ElementsGroup 17 Elements


2/14

Group 17 elementsGroup 17 elements

Fluorine, FFluorine, F

Chlorine, ClChlorine, Cl

Bromine, BrBromine, Br

Iodine, IIodine, I

Astatine, AtAstatine, At

known asknown as halogens.halogens.

reactive nonreactive non--metalmetal

exist asexist as diatomicdiatomicmoleculemolecule ( F( F22 , Cl, Cl22 ,,BrBr22 , I, I22 , At, At22 ))


3/14

Physical PropertiesPhysical Properties

ElementElement ProtonProtonnumbernumber

AtomicAtomicradius /radius /nmnm

MPMP

(( C)C)

BPBP

(( C)C)

DensityDensity

(g cm(g cm--33ElectroElectro--negativitynegativity

FF22 99 0.0710.071 --220220 --188188 0.00170.0017 4.04.0

ClCl22 1717 0.0990.099 --101101 --3535 0.00320.0032 3.03.0

BrBr22 3535 0.1140.114 --77 5959 3.133.13 2.82.8

II22 5353 0.1330.133 114114 184184 4.944.94 2.52.5


4/14

Halogens

Low melting& boiling

point

Low

densities

Poor conductor

of heat &electricity


5/14

Down the group,Down the group,

atomic sizeatomic size

number of shells occupied with e number of shells occupied with e

MP & BPMP & BP

Molecular size , Van der Waals forces ofMolecular size , Van der Waals forces ofattraction between molecules become stronger.attraction between molecules become stronger.More heat energy is required to overcome forcesMore heat energy is required to overcome forcesduring melting / boiling.during melting / boiling.


6/14


DensityDensity

in atomic mass > in volume in atomic mass > in volume

Electronegativity Electronegativity

Atomic sizeAtomic size,,outermost shell become furtheroutermost shell become further

away from nucleus. Strength of nucleus to pullaway from nucleus. Strength of nucleus to pulle become weaker.e become weaker.


7/14


colour becomes darkercolour becomes darker

FF22 Pale yellowPale yellowgasgas

ClCl22 GreenishGreenish--yellowyellowgasgas

BrBr22 ReddishReddish--brownbrownliquidliquid

II22 PurplishPurplish--blackblacksolidsolid


8/14

Chemical PropertiesChemical Properties

All halogen atoms have 7 valence eAll halogen atoms have 7 valence e..

1 more e1 more e is needed to achieve stableis needed to achieve stable

noble gas electron arrangement.noble gas electron arrangement.FF + e+ e FF

(2.7 )(2.7 ) (2.8 )(2.8 )

ClCl ++ ee ClCl

(2.8.7 )(2.8.7 ) (2.8.8 )(2.8.8 )

BrBr ++ ee BrBr

(2.8.18.7 )(2.8.18.7 ) (2.8.18.8 )(2.8.18.8 )


9/14

Chemical PropertiesChemical Properties

ReactivityReactivity down the group. down the group.

FF22 ClCl22 BrBr22 II22 AtAt22

less reactiveless reactive

Atomic size down the group. OutermostAtomic size down the group. Outermostoccupied shell becomes further away fromoccupied shell becomes further away fromnucleus. Strength of nucleus to attract 1 morenucleus. Strength of nucleus to attract 1 moreee. Reactivity from F. Reactivity from F22toAttoAt22..


10/14

Halogen + HHalogen + H22OO

Solubility of halogens in HSolubility of halogens in H22OO down the group.down the group.

ClCl22(g)(g) + H+ H22OO(l)(l) HClHCl(aq)(aq) + HOCl+ HOCl(aq)(aq)

hydrochlorichydrochloric acid hypochlorous acid acid hypochlorous acid

The acid solutions formedThe acid solutions formed turn blue litmusturn blue litmuspaper red before white.paper red before white. This is due to theThis is due to thepresence of hypochlorous acid which is also apresence of hypochlorous acid which is also ableaching agent.bleaching agent.

Chlorine gas is prepared by mixing KMnOChlorine gas is prepared by mixing KMnO44crystals with concentrated HCl.crystals with concentrated HCl.

88HClHCl(aq)(aq) + KMnO+ KMnO44(s)(s) KCl KCl(aq)(aq) + MnCl+ MnCl22(aq)(aq) + 4H+ 4H22OO(l)(l) ++5/2Cl5/2Cl22(g)(g)


11/14

Halogen + IronHalogen + Iron

Halogens react with hot iron to formHalogens react with hot iron to form iron (III)iron (III)halides (brown solid).halides (brown solid).

2Fe2Fe(s)(s) + 3Cl+ 3Cl22(g)(g) 2FeCl 2FeCl33(s)(s)

Iron chlorine Iron (III)chloride

Soda lime ( CaO + NaOH ) is used to absorbthe excess poisonous chlorine gas/ brominevapor from escaping into the surroundings.


12/14

Halogen + NaOHHalogen + NaOH

Halogens react with cold NaOH solution toHalogens react with cold NaOH solution toproduceproduce waterwater & colourless solution containing& colourless solution containingsalts of sodium halide & sodium halate (I).salts of sodium halide & sodium halate (I).

ClCl22(g)(g) + NaOH+ NaOH(aq)(aq) NaCl NaCl(aq)(aq) + NaOCl+ NaOCl(aq)(aq) + H+ H22OO(l)(l)

sodium chloride sodium chloratesodium chloride sodium chlorate

Reactivity of halogens with NaOHReactivity of halogens with NaOH from Cl from Cl22 totoII22..


13/14

Safety precautionsSafety precautions

Halogens vapor is harmful &Halogens vapor is harmful &poisonous.poisonous.

Must be handle in fume chamber.Must be handle in fume chamber. Wear safety goggles & gloves.Wear safety goggles & gloves.


14/14

Having no inclination to thinkHaving no inclination to thinkin a negative way,in a negative way,

all that we hear will beall that we hear will behelpful & constructive to us.helpful & constructive to us.

~ Still Thoughts~ Still Thoughts

chapter 4d group 17 elements

Documents