Inert/Noble Gases: Inorganic Chemistry.ppt

Nobel Gases

1. NOBLE GASES
Hey Class, I am here to present some facts about Noble
Gases.

3. Where are the noble
gases?
The elements in group 18, on the right of the periodic table, are
called thenoble gases.
He
Rn
Xe
Kr
Ar
Ne
helium
neon
argon
krypton
xenon
radon

4. Group 18: The Nobel gases
•Thenoblegases,alsoknownastheinertgasesor
raregases,arelocatedinGroupVIIIAor18of
theperiodictable.
•Group18issometimescalledGroup0.
•Thisgroupisasubsetofthenonmetals.
•Thenoblegasesare;helium(He),neon(Ne),
argon(Ar),krypton(Kr),xenon(Xe),radon
(Rn)andOganesson(Og).
•Theelementshavea[core]ns
2
np
6
electron
configurationwithacompleteoctet.(nisthe
periodnumber)
•Theirclosedshellelectronconfigurationmakes
themhaveaverylowreactivity.
The Nobel gases

5. Group 18: The Nobel gases
•Noblegaseshaveafullvalenceshell.
•Thenoblegasesarethesmallestelementsintheirrespectiveperiods,withthe
highestionizationenergies.
•Noblegaseshaveverylowmeltingandboilingpoints.
•OnlyKr,Xe,andRnareknowntoformcompounds.
•Xeisthemostreactivenoblegasandexhibitsallevenoxidationstatesfrom
+2to+8.
•Verylowelectronegativities
•Nocolor,odor,orflavorunderordinaryconditions
•Nonflammable
•Atlowpressure,theywillconductelectricityandfluoresce
The Nobel gases

6. Group 18: The Nobel gases
•Allthenoblegasesoccurintheatmosphereasmonatomicgases.
They are monatomic, which means they exist as individual atoms. Most
other gases are diatomic.
•Togethertheymakeup1%(bymass)oftheatmosphere.
•ArgonisthethirdmostabundantgasintheatmosphereafterNandO.
The Nobel gases
SourcesoftheNobleGases
•AllofthenoblegasesexceptHeandRnareobtainedbythefractionaldistillation
ofliquidair.
•Themajorsourceofheliumisfromthecryogenicseparationofnaturalgas.
•Radon,aradioactivenoblegas,isproducedfromtheradioactivedecayofheavier
elements,includingradium,thorium,anduranium.
•Element118(Og)isaman-maderadioactiveelement,producedbystrikinga
targetwithacceleratedparticles.

7. ThegasesHe,Ne,Ar,KrandXealloccurinatmosphere.
AmixtureofnoblegaseswasfirstobtainedbyCavendishin1784.HeremovedN
2fromairby
addingexcessO
2andsparking.TheNO
2formedwasabsorbedbyNaOHsolutionandexcessO
2was
removedbyburningwithS.Thisgavesmallvolumeofunreactivegas.
Argonisabundantandcheapestandcanberecoveredbyfractionaldistillatonofliquidair.
Othernoblegasesaremuchlessabundant.
Thenonradioactivenoblegasesareallproducedindustriallybyfractionaldistillationofliquidair.
Rnisradioactiveandproducedbydecayofradiumandthoriumminerals.Theconvenientsourceis
226
Ra.
88
226
Ra
222
86Rn+
4
2He

8. Group 18: The Nobel gases
Uses of noble gases
•Thenoblegasesareusedtoforminertatmospheres,toprotectspecimens,and
topreventchemicalreactions(topreventoxidation).
•Argonisalsousedtofillsometypesoflightbulbs,whereitconductsheat
awayfromthefilament.ThelargestuseofArgonistoprovideaninert
atmosphereformetallurgicalprocesses.Smalleramountsareusedingrowing
siliconandgermeniumcrystalsfortransistorsandinelectriclightbulbs,
fluorscentlamps,radiovalves.
•Heliumhasthelowestboilingpointofanyliquidanditisusedincryoscopy
toobtainverylowtemp.Requiredforsuperconductivityandlasers.
•Itisusedascoolinggasinnuclearreactorandastheflowgasingas
liquidchromatography.
•Itisusedinweatherballonsandairships.ThoughHydrogenhas
lesserdensityandischeaperandmorereadilyavailablethanHe.

9. •Hydrogenishighlyflammable.ThusonsafetyguardsHeisusedin
preferenceofHydrogeninairship.
•Heliumisusedinpreferencetonitrogentodilutedioxygeninthegas
cylindersusedbydivers.Thisisbecausedinitrogenisquitesolublein
bloodsosuddenchangeinpressurecausesdegassingandgivesbubblesof
nitrogengasinblood.Thiscausedpainfulconditioncalled“bends”
•Kryptongivesanintensewhitelightwhenanelectricalcurrentispassed
throughitanditisusedinairportsforthererunwaylightsused:
Inlasersforeyesurgery,tostopbleedingontheretina.
Inlighthousesandothertypesoflamps.
•Xenonisused:
Invarioustypesofelectrontubes,lamps,lasersandinhighspeed
photographicflashtubes
.

10. •SmallamountofNeisusedinneondischargetubewhichgivethe
familiarreddishorangeglowofneonsign.
•Radonisused:
Totreatcancerbyradiotherapy,becauseitisradioactive.
However,becauseradonisradioactive,itisalsoanenvironmental
hazard

11. Group 18: The Nobel gases
•Atomicmass,boilingpoint,andatomicradiiINCREASEdownagroupin
theperiodictable.
•ThefirstionizationenergyDECREASESdownagroupintheperiodictable.
•Thenoblegaseshavethelargestionizationenergies,reflectingtheirchemical
inertness.
•DownGroup18,atomicradiusandinteratomicforcesINCREASEresulting
inanINCREASEDmeltingpoint,boilingpoint,energyofvaporization,and
solubility.
•TheINCREASEindensitydownthegroupiscorrelatedwith
theINCREASEinatomicmass.
•Becausenoblegases’outershellsarefull,theyareextremelystable,tending
TheAtomicandPhysicalProperties

12. Element Outer
electronic
configuration
Vander
Wall's
radius
(Å)
First
IE
(kj mol
-1
)
m.pt.
(K)
b.pt.
(K)
∆H
fux
(kj mol
-1
)
∆H
vap
(kj mol
-1
)
He
Ne
Ar
Kr
Xe
Rn
1s2
2s
2
2p
6
3s
2
3p
6
4s
2
4p
6
5s
2
5p
6
6s
2
6p
6
-
1.31
1.74
1.89
2.10
2.15
2372
2080
1519
1351
1170
1037
-
24.4
83.6
116
161
200
4.2
27.1
87.3
120
166
211
0.02
0.33
1.18
1.64
2.3
2.9
0.08
1.77
6.5
9.0
12.6
16.4
Physical Properties Noble gases

13. Group 18: The Nobel gases
SelectedPropertiesofGroup8A
Elements

14. CHEMICAL INERTNESS OF NOBLE GASE S
Chemical Inertness of these gases is supported by the reasons:
i)The atoms have stable completely field electronic shells
ii)They have high ionisation energies
iii)The noble have almost zero electron affinities.
Therefore, they do not have any tendency to gain, lose or share electrons with
other atoms.
 Recentstudieshaveshownthatundercertainspecificcondition,theyenterinto
chemicalcombinationsandformsomerarechemicalcompounds.
 Thespecificconditionsandthetypesofcompoundsformedbythesegasesare
disusedbelow-
 Under excited condition:-Sparking Helium at low pressure in presence of
mercury, tungsten etc. forms compounds like HgHe
2, HgHe
10, WHe
2.
 Helium compounds are also fromed in discharge tubes like BiHe
2, FeHe, Pt
3He,
PdHe. These compounds are not considered as true chemical compounds as He is
absorbed on the surface .

15. •Compoundsformedthroughco-ordination-Argonformsanumberofunstablecompound
withvaryingno.ofBF
3moleculese.g.Ar.BF
3,Ar.6BF
3
•Inthesecompounds,argonatomsdonatesapairofelectronstoBoronatomofBF
3.
•IncaseofhighercompoundsfluorineatomsofBF
3alsodonatepairofelectrons.
•Hydratesofnoblegases:Thehydratesofthesegasesareformedbycompressingthegases
withwatere.g.,Xe.6H
2O.
•Compoundsformedbyphysicaltrapping(Clathrates)TheinertgasesArgon,Kryptonand
Xenonformsolidcompoundswithcertainorganicmoleculessuchasphenoland
hydroquinoneunderpressure.Insuchcompoundstheinertgasareenclosedinthecrystal
latticeoforganiccompoundsknownasclathratesorcagecompounds.
•

16. Group 18: The Nobel gases
•Theelementshaveacompleteoctet,predictthattherewouldbenochemistry
forthenoblegases.
•However,numerousgroup18compoundsareknown,althoughtheymaybe
veryunstableandexplosive.
•HeandNearechemicallyinertandtheydonotformanycompounds.
Theirchemicalinertnessisduetoveryhighionizationenergy,zeroelectron
affinityandtheabsenceofvacantd-orbitalsinvalenceshell.
•Ar,KrandXewillshowsomereactivity
duetolowionizationpotentialsandpresenceofvacantd-orbitalsin
valenceshell.
•XeismorereactivethanArandKr
duetoit'slowionisationenergy.
•Radonisradioactiveanditwillnotshowchemicalreactivity.
CompoundsoftheNobelGases(Reactivity):

18. Group 18: The Nobel gases
•KryptonformsonlyoneknownstableneutralmoleculeKrF
2.
•Xeshowstendencytoloseelectronsinmanyofit'sreactions.Therefore,Xe
combineswithonlymoreelectronegativeelementslikeFandOor
electronegativegroups.
•XedoesnotcombinewithlesselectronegativeelementslikeCl
2orN
2.
CompoundsoftheNobelGases(Reactivity):

19. Group 18: The Nobel gases
TheElements(Xenon)
•Xenonisuniqueforbeingthefirstnoblegaselementtobesynthesized
intoacompound.
•Discoveredon1898bySirWilliamRamsay.
•Xenonispresenttoasmallextentintheatmosphere(lessthanoneppmby
volume).
•Metallicxenonisproducedbyapplyingseveralhundredkilobarsof
pressure.
•In1962thefirstnoblegascompoundwasproducedbyNeilBartlett,
combiningxenon,platinumandfluorine.
•Itisnowpossibletoproducexenoncompoundsinwhichtheoxidation
statesrangefrom+2to+8.
•Mostoftheknownxenoncompoundscontainthestronglyreducing
fluorineoroxygenatoms.

21. Xenon-fluorine compounds
XeF
2, XeF
4and XeF
6
Preparation : By the direct reaction of elements under appropriate
experimental conditions.
Properties:Theyarereadilyhydrolysedevenbytracesofwater.
673K, 1bar
873K, 7bar
573K, 60-70bar
XenonCompoundsandtheirMolecularStructure
Group 18: The Nobel gases
FluorineistheonlyelementthatdirectlyreactswithXenon.

22. Group 18: The Nobel gases
•XenonHalidesarereactivewithothercompoundssuchaswater.
XeF
2+3H
2O→XeO
3+6HF
•TheXehasatotalof8outsideshellelectronswhiletheFluorine7valence
electrons.
•Xe'soutsideshellelectronsareveryfarawayfromthecenter,therefore
Xenoncannotpossiblyattractalloftheelectrons.
•Fluorineissmaller,thereforeishasastrongerpositiveattractiontothefew
electronsithasleft.
•FluorineistheonlyelementthatreactswithXebecauseitisthemost
electronegative.
•Inotherwords,itistheonlyelementthatisstrongenoughtopullelectrons
outofthestablexenon.
XenonCompoundsandtheirMolecularStructure

23. Xenon-oxygen compounds
XeO
3 XeOF
4and XeO
2F
2
Hydrolysis of XeF
4and XeF
6with water gives
XeO
3.
XeO
3
6XeF
4+ 12 H
2O → 4Xe + 2XeO
3+ 24 HF + 3
O
2
XeF
6+ 3 H
2O → XeO
3+ 6 HF
XeO
3 is a
colourless
explosivesolid
and
hasapyramidal
molecular
structure
sp
3
Hybridization
Group 18: The Nobel gases
XenonCompoundsandtheirMolecularStructure

24. Partial hydrolysis of XeF
6gives oxyfluorides, XeOF
4and
XeO
2F
2.
XeOF
4and XeO
2F
2
XeF
6 + H
2O → XeOF
4+ 2 HF
Xenon oxytetrafluoride
XeF
6+ 2 H
2O → XeO
2F
2+ 4HF
Xenon dioxydifluoride
XeOF
4isacolourlessvolatileliquidandhasasquarepyramidal
molecularstructure
Group 18: The Nobel gases
XenonCompoundsandtheirMolecularStructure
Square pyramidal

25. F
F
O
O
Xe
sp
3
d
2
Hybridization
↑
↓
sp
3
d
Hybridization
Group 18: The Nobel gases
XeO
2F
2 XeOF
4

26. Structures of several known xenon compounds
Group 18: The Nobel gases

27. Xenonformsalargeno.ofcompoundswithoxygenandfluorineindifferent
oxidationstates.Thesearexenonfluorides,xenonoxidesandxenon
oxifluorides.1.XeF
2
Preparation.
1.Xenondifluorideisbestpreparedbyheatingamixtureofxenonandfluorine
inmolecularratioof2:1at400
0
Cinasealednickeltube.Oncoolingquickly,a
colourlesssolidXeF
2isobtained.
Ni
Xe+F
2 XeF
2
400
0
C
Properties
1.Xenondifluorideisacolourless,crystallinesolidwhichmeltsat129
0
C.
2.Itreactswithhydrogentogivehydrogenfluorideandxenon.
XeF
2+H
2 Xe+2HF
Compounds of noble gases-

28. 3.Itgivessubstitutionreactionswithstrongprotonicacids.
XeF
2+HX FXeX+HF
FXeX+HX XeX
2+HF
Where X=CIO
-
4CF
3COO
-
,SO
3F
-
etc.
4.Ithydrolysesslowlybutcompletelyinacidic,neutraloralkalinesolutions.
2 XeF
2+2H
2O 2 Xe+4HF+O
2
2 XeF
2+4NaOH 2Xe+4NaF+O
2+2H
2O
5. It oxidizes iodine in the presence of BF
3to give IF.

29. 2.XeF
4
Preparation.
Itispreparedbyheatingamixtureofxenonand
fluorine,inanickelvassal,at400
0
Cunderpressureof
5-6atm.
Itcanalsobesynthesizedbypassinganelectric
dischargethroughamixtureofxenonandfluorineat-
78
O
C.
Properties of XeF
4are:
Itisacolorless,crystallinesolid,withm.pt.117.1
0
c,
sublimesreadily.
OxidizedbyhydrogentoHFat30
0
C.
AstrongerfluorinatingagentthanXeF
2

30. 3 . XeF
6
Preparation.
1.Itispreparedbyheatingxenonwithexcessoffluorine(inthe
molarratioof1:20)inanickelvesselat250-300
0
Cunderpressure
of50-60atm.
Xe+3F
2 XeF
6
2.ItcanalsobeobtainedbytheoxidationofXeF
4withO
2F
2under
pressure.
XeF
4+O
2F
2-130
0
cXeF
6+O
2

31. 2XeF
6+SiO
2 2XeOF
4 +SiF
4
2XeOF
4+SiO
2 2XeO
2F
2+SiF
4
2XeO
2F
2+SiO
2 2XeO
3+SiF
4
(explosive)
Properties:-Crystalline substance, m.pt. 49.5
0
C, Mostly volatile,
all the fluorides of xenon are greenish yellow colour vapour . It
is extremely reactive. Therefore, it cannot be stored in glass or
quartz vessels because of the following reactions which finally
give the dangerously explosive xenon trioxide.

32. 2It reacts with fluoride ion acceptors to form adducts.
XeF
6+PtF
5 XeOF
4+PtF
5 [XeF
5]
+
[PtF
6]
-
XeF
6+SbF
5 XeF
6.SbF
5 [XeF
5]
+
[SbF
6]
-
XeF
6+AsF
5 XeF
6.AsF
5 [XeF
5]
+
[AsF
6]
-

33. 4.XeOF
4
Preparation:
(i)XenonOxytetraflourideispreparedbypartial
hydrolysisofXenonhexaflouride
XeF
6
+
H
2O XeOF
4+2HF
(ii)bytheactionofXeF
6onsilicondioxide
2XeF
6
+
SiO
2 XeOF
4+SiF
4

34. SoonastheyellowcolourofXeF
6disappears,thecontents
areimmediatelyquenchedwithsolidCO
2.Itisdoneto
avoidtheformationofXeO
3(explosive)as:
XeOF
4+SiO
2 XeO
3+SiF
4

35. Properties.
1.Itisacolourlesscompoundmeltingat-46
o
C.
2Itisreducedbyhydrogentoxenon.
XeOF
4+3H
2 Xe+H
2O+4HF
3Itreactswithwaterorsilicatoformanotheroxyfluoride,
XeO
2F
2,in;whichxenonremainsinthesameoxidation
state.FurtherreactiongivesexplosivecompoundXeO
3

36. 4XeOF
4+H
2O XeO
2F
2+2HF
XeO
2F
2+H
2O XeO
3+2HF
2XeOF
4+SiO
2 2XeO
2F
2+SiF
4
2XeO
2F
2+SiO
2 2XeO
3+SiF
4

37. Valence bond treatment and MO treatment for XeF
2

39. Structure of Some Xenon Compounds
FormulaName Oxid
n
state
m.pt. (
o
C)Structure
XeF
2
Xenon
difluoride
+2 129 Linear
XeF
4
Xenon tetra
fluoride
+4 117 Square Planner
XeF
6
Xenon
hexafluoride
+6 49.6 Distorted octahedron
XeO
3
Xenon trioxide+6 ExplodesPyramidal tetrahedral with
one corner un occupied

40. XeO
2F
2 Xenon dioxy
difluoride
+630.8Trigonal lipyramid (with
one position
unoccupied)
XeOF
4 Xenon oxy
tetrafluoride
+6-46Square pyramidal
(octahedral with one
position un occupied
XeO
4 Xenon tetra oxide+8-35.9Tetrahedral
XeO
3F
2 Xenon trioxy
difluoride
+8-54.1Trigonal bipyramidal
Ba
2[XeO
6]-4Barium
perxenate
+8 octahedral

41. Structure and Bonding in Xenon Compounds
Formula Structure No.
of e
pairs
No. of
lone
pairs
VSEPR
(Explanation of structure)
XeF
2 Linear 5 3 Fiveelectronpairsformtrigonalbipyramidalwith
threelonepairsatequatorialpositions
XeF
4 Square
Planner
6 2 Sixelectronpairsformoctahedronwithtwo
positionsoccupiedbylonepairs
XeF
6 Distorted
octahedron
7 1 Pentagonalbipyramidalorcappedoctahedronwith
onelonepair
XeO
3 Pyramidal 7 1 Threeπbondssothattheremainingfourelectron
pairsformatetrahedronwithonecorneroccupied
byalonepairs.

42. Formula Structure No. of e
pairs
No. of
lone
pairs
VSEPR
(Explanation of structure)
XeO
2F
2 Trigonal
lipyramid
7 1 Twoπbondssoremainingfiveelectron
pairformtrigonalbipyramidwithone
equatorialpositionoccupiedbyalone
pair
XeOF
4 Square
pyramidal
7 1 Oneπbondsoremainingsixelectron
pairsformanoctahedronwithone
positionoccupiedbyalonepair.
XeO
4 Tetrahedral 8 0 Fourπbondssoremainingfourelectron
pairformatetrahedron
XeO
3F
2 Trigonal
bipyramid
8 0 Threeπbondssoremainingfiveelectron
pairsformtrigonalbipyramid
Ba
2[XeO
6] Octahedral 8 0 Twoπbondssoremainingsixelectron
pairformanoctahedron.

43. . .
Xe
. .
XeF
4 sp
3
d
2
Xe
F
..
F
..
Molecule Type of Hybridization
Geometrical Shape
XeF
2
F
F
F F

44. XeF
6 sp
3
d
3
. .
Xe
xe
XeO
3 sp
3
F
F
F
F
F
F
Geometrical Shape
Molecules & Type of hybridization

45. xe
O
F
O
XeOF
4 sp
3
d
2
Xe
F
XeO
2F
2 sp
3
d
O
F F
F
F
. .
. .
F
XeO
2F
4 Sp
3
d
2
Xe
O
F F
F
F
O

46. XeOF
4 Sp
3
d
2
Xe
O
F F
F
O
XeO
6 Sp
3
d
2
Xe
O O
O
F
O
-4
-4
O
. .

47. SignificanceofNoblegasesindevelopmentoftheoretical
chemistry.
1.InElucidationofdistributionofelectronsinatom
2.Inperiodicclassification
3.Inthedevelopmentofelectronictheoryofvalency
4.Inradioactivity.

49. Thank you