CHAPTER – 8
THE D AND F BLOCK ELEMENTS
havepartlyorincompletelyfilled(n-1)dorbitalintheir
elementarystates.
D-blockelements:
Thed-blockelementsarecalledtransitionmetals(belonging
togroup3to12)andhavevalenceelectronsinthed-orbitals.
Itsstandardelectronicconfigurationis(n-1)d1-10ns1-2where
(n-1)representsthefrontshell(lastbutonlyone).
Definition: initiallytheywerenamed‘transitionelements’
becausetheirpropertieswerefoundtobetransitional
betweensandpblockelements.
However,IUPACdefinitionisasfollows,
Transitionmetalsaremetalswhichhaveincompleted
subshelleitherwhichhaveoneormoreunpaireddelectrons
intheirgroundstateorintheircommonoxidationstatecan
becalledtransitionelements.
Introductiontod-BlockElements
Thed-blockelementsaredefinedastheelementsfrom Note
periodictableinwhich,lastelectronentersintothe‘d-orbital’
ofthepenultimateshelli.e.(n-1)dorbital.Where‘n’isthelast group-12elementsi.e.,Zn,CdandHghavecompletely
shell.
filledd-orbitalbothintheirgroundstateandintheir
Thed-blockelementsarealsocalledtransitionelements,
oxidationstatethustheyarenotconsideredtransition
becausetheirpropertiesareintermediatebetweenthe
propertiesofhighlyelectropositives-blockelementsand elementsbutnonethelessarestudiedunderd-block.
highlyelectronegativep-blockelements.Transitionelements
, Alotofelementsdonotpossessunpairedelectronsintheir AccordingtoClassicalorearlierconceptreductionisa
groundstatebutdefinitionhelpsidentifythemastransition processwhichinvolvestheadditionofhydrogenorany
elements.Eg.–Copper electropositiveelementortheremovalofoxygenorany
electronegativeelement.
Electronicconfigurationofis:1s22s22p63s23p64s13d10.As
wecansee,ithasacompletelyfilledd-orbitalinitsground Accordingtoelectronicconceptreductionisdefinedasthe
statebutinitscommonoxidationstatei.e.,+2, processinwhichanatomoriongainsoneormoreelectrons.
ElectronicconfigurationofCu2+is:1s22s22p63s23p64s03d9 Whyared-Blockelementscalledtransitionelements?
andithasanunpairedelectronthusitcanbecalleda Thepositionofd-blockelementsareinbetweens−blockand
transitionelement.Asimilarcaseisobservedforsilver. p−blockelementsinperiodictable.Thesed-blockelements
are called transition elements because they exhibit
Thepossessionofunpaireddandfelectronsmakestransition transitionalbehaviourbetweens−andp−elements.
elementsdifferentfromsandpblockelementsandhence
therestudyiscarriedoutseparately. Theirpropertiesaretransitionalbetweenhighlyreactive
metallicelementsofs−blockwhicharetypicallyionic
Someimportantconcepts compoundsandelementsofp−blockwhicharelarge-
EnthalpyofAtomisation: covalent.
Enthalpyofatomization,ΔaH0,isthechangeinenthalpy F-BlockElements:
whenonemoleofbondsiscompletelybrokentoobtainatoms Theelementsoffblockarelanthanidesandactinidesandare
inthegasphase.Forexample:atomizationofmethane calledgeneticmutationsduetotheirplacementinthe
molecule. periodictableduetotheactivationofelectrons.Theorbitals
CH4 (g)→C(g)+4H(g) ΔaH0=1665.0kJmol-1 oftheelectronshellarefilledwith“n-2.”Thereareahigh
numberoffourteenelectronsthatcanresideinorbitals.
Fordiatomicmolecules,theenthalpyofatomizationisequal
totheenthalpyofbonddissociation.Forexample:the Lanthanoids:
atomizationofdihydrogenmolecule. The14elementsthatimmediatelyfollowlanthanum,namely,
H2 (g)→2H(g); ΔaH0=435.0kJmol-1 Cerium(58)toLutetium(71)arecalledlanthanoids.They
belongtothefirstseriesofinner-transitionelements.
MetallicBonding: Lanthanum(57)hassimilarproperties.Therefore,they
Metallicbondingisatypeofchemicalbondingthatarises calledaslanthanoids.
fromtheelectrostaticattractiveforcebetweenconduction
Actinoids:
electrons(intheformofanelectroncloudofdelocalized
The14elementsimmediatelyafteractinium(89),with
electrons)andpositivelychargedmetalions. atomicnumbers90(Thorium)to103(Lawrencium)are
Lanthanoidcontraction:
calledactinoids.Theyareinthesecondphaseofinner-
Lanthanidesaretherareearthelementsofthemodern
transitionelements.Actinium(89)hassimilarfeatures.
periodictable,i.e.theelementswithatomicnumbersfrom58 Therefore,theycalledasactinoids.
to71,followingtheelementLanthanum.
Why are f-block elements called inner transition
Theatomicsizeortheionicradiioftripositivelanthanide elements?
ionsdecreasesteadilyfromLatoLuduetoincreasingnuclear Fblockelementsarecalledinnertransitionelementsbecause
chargeandelectronsenteringtheinner(n-2)forbital.This thelastelectronenterstheanti-penultimateshell,whichis
gradualdecreaseinthesizewithanincreasingatomic innertothepenultimateshellinwhichthelastelectronofd-
number is called lanthanoid contraction. Lanthanoid blockelementsenters.
contractionisalsoknownaslanthanidecontraction ElectronicConfigurationd-BlockElements
Generalelectronicconfigurationoffourseriesofd-block
StandardElectrodePotential:
elementsaregivenbelow.
Understandardconditions,thestandardelectrodepotential
3dseries:[Ar]3d1-104S1-2
occursinanelectrochemicalcellsaythetemperature=298K,
4dseries:[Kr]4d1-105S0-2
pressure=1atm,concentration=1M.Thesymbol‘Eocell’ 5dseries:[Xe]5d1-106S2
representsthestandardelectrodepotentialofacell. 6dseries:[Rn]6d1-107S2
OxidationandReduction: AbnormalElectronicConfigurationofChromiumAndCopper
AccordingtoClassicalorearlierconceptoxidationisa amongdBlockElements
processwhichinvolvestheadditionofoxygenorany Chromium(24Cr)haselectronicconfiguration
electronegativeelementortheremovalofhydrogenorany (Expected):[Ar]3d44S2
electropositiveelement. (Observed):[Ar]3d54s1
Copper(29Cu)haselectronicconfiguration
Accordingtoelectronicconceptoxidationisdefinedasthe (Expected):[Ar]3d94s1
processinwhichanatomorionlosesoneormoreelectrons. (Observed):[Ar]3d104s1
, FourTransitionseries
Explanation 1. 3d-Transitionseries. Transitionelementswithan
due to more stability of half –filled and atomicnumber21(Sc)to30(Zn)andwithan
incomplete3dorbitalarecalledthefirstseriesof
completely filled orbital. mutations.
PhysicalProperties
Thetransitionmetalsarehardandtough.Theyhavelow
volatilitybutZn,CdandHgareanexception.
Theyhavehighmeltingandboilingpointsduetothegreater
quantityofelectronsfrom(n-1)dalongwiththenselectrons
metallic
2. 4d-Transitionseries. Itcontainselementswithan
atomicnumber39(Y)to48(Cd)andhasanincomplete
4dorbital.Itiscalledthesecondversionoftheversion.
Metalspossessinghighboilingpointarenobleintheir
Themetalsbelongingtosecondandthirdserieshavegreater
enthalpiesofatomisationthantheelementsbelongingtofirst
series.
3. 5d-Transitionseries. Transitionelementswith
atomicnumbers57(La),72(Hf)to80(Hg)andwithan
incomplete orbital 5d are called the third
transformationseries.
THE D AND F BLOCK ELEMENTS
havepartlyorincompletelyfilled(n-1)dorbitalintheir
elementarystates.
D-blockelements:
Thed-blockelementsarecalledtransitionmetals(belonging
togroup3to12)andhavevalenceelectronsinthed-orbitals.
Itsstandardelectronicconfigurationis(n-1)d1-10ns1-2where
(n-1)representsthefrontshell(lastbutonlyone).
Definition: initiallytheywerenamed‘transitionelements’
becausetheirpropertieswerefoundtobetransitional
betweensandpblockelements.
However,IUPACdefinitionisasfollows,
Transitionmetalsaremetalswhichhaveincompleted
subshelleitherwhichhaveoneormoreunpaireddelectrons
intheirgroundstateorintheircommonoxidationstatecan
becalledtransitionelements.
Introductiontod-BlockElements
Thed-blockelementsaredefinedastheelementsfrom Note
periodictableinwhich,lastelectronentersintothe‘d-orbital’
ofthepenultimateshelli.e.(n-1)dorbital.Where‘n’isthelast group-12elementsi.e.,Zn,CdandHghavecompletely
shell.
filledd-orbitalbothintheirgroundstateandintheir
Thed-blockelementsarealsocalledtransitionelements,
oxidationstatethustheyarenotconsideredtransition
becausetheirpropertiesareintermediatebetweenthe
propertiesofhighlyelectropositives-blockelementsand elementsbutnonethelessarestudiedunderd-block.
highlyelectronegativep-blockelements.Transitionelements
, Alotofelementsdonotpossessunpairedelectronsintheir AccordingtoClassicalorearlierconceptreductionisa
groundstatebutdefinitionhelpsidentifythemastransition processwhichinvolvestheadditionofhydrogenorany
elements.Eg.–Copper electropositiveelementortheremovalofoxygenorany
electronegativeelement.
Electronicconfigurationofis:1s22s22p63s23p64s13d10.As
wecansee,ithasacompletelyfilledd-orbitalinitsground Accordingtoelectronicconceptreductionisdefinedasthe
statebutinitscommonoxidationstatei.e.,+2, processinwhichanatomoriongainsoneormoreelectrons.
ElectronicconfigurationofCu2+is:1s22s22p63s23p64s03d9 Whyared-Blockelementscalledtransitionelements?
andithasanunpairedelectronthusitcanbecalleda Thepositionofd-blockelementsareinbetweens−blockand
transitionelement.Asimilarcaseisobservedforsilver. p−blockelementsinperiodictable.Thesed-blockelements
are called transition elements because they exhibit
Thepossessionofunpaireddandfelectronsmakestransition transitionalbehaviourbetweens−andp−elements.
elementsdifferentfromsandpblockelementsandhence
therestudyiscarriedoutseparately. Theirpropertiesaretransitionalbetweenhighlyreactive
metallicelementsofs−blockwhicharetypicallyionic
Someimportantconcepts compoundsandelementsofp−blockwhicharelarge-
EnthalpyofAtomisation: covalent.
Enthalpyofatomization,ΔaH0,isthechangeinenthalpy F-BlockElements:
whenonemoleofbondsiscompletelybrokentoobtainatoms Theelementsoffblockarelanthanidesandactinidesandare
inthegasphase.Forexample:atomizationofmethane calledgeneticmutationsduetotheirplacementinthe
molecule. periodictableduetotheactivationofelectrons.Theorbitals
CH4 (g)→C(g)+4H(g) ΔaH0=1665.0kJmol-1 oftheelectronshellarefilledwith“n-2.”Thereareahigh
numberoffourteenelectronsthatcanresideinorbitals.
Fordiatomicmolecules,theenthalpyofatomizationisequal
totheenthalpyofbonddissociation.Forexample:the Lanthanoids:
atomizationofdihydrogenmolecule. The14elementsthatimmediatelyfollowlanthanum,namely,
H2 (g)→2H(g); ΔaH0=435.0kJmol-1 Cerium(58)toLutetium(71)arecalledlanthanoids.They
belongtothefirstseriesofinner-transitionelements.
MetallicBonding: Lanthanum(57)hassimilarproperties.Therefore,they
Metallicbondingisatypeofchemicalbondingthatarises calledaslanthanoids.
fromtheelectrostaticattractiveforcebetweenconduction
Actinoids:
electrons(intheformofanelectroncloudofdelocalized
The14elementsimmediatelyafteractinium(89),with
electrons)andpositivelychargedmetalions. atomicnumbers90(Thorium)to103(Lawrencium)are
Lanthanoidcontraction:
calledactinoids.Theyareinthesecondphaseofinner-
Lanthanidesaretherareearthelementsofthemodern
transitionelements.Actinium(89)hassimilarfeatures.
periodictable,i.e.theelementswithatomicnumbersfrom58 Therefore,theycalledasactinoids.
to71,followingtheelementLanthanum.
Why are f-block elements called inner transition
Theatomicsizeortheionicradiioftripositivelanthanide elements?
ionsdecreasesteadilyfromLatoLuduetoincreasingnuclear Fblockelementsarecalledinnertransitionelementsbecause
chargeandelectronsenteringtheinner(n-2)forbital.This thelastelectronenterstheanti-penultimateshell,whichis
gradualdecreaseinthesizewithanincreasingatomic innertothepenultimateshellinwhichthelastelectronofd-
number is called lanthanoid contraction. Lanthanoid blockelementsenters.
contractionisalsoknownaslanthanidecontraction ElectronicConfigurationd-BlockElements
Generalelectronicconfigurationoffourseriesofd-block
StandardElectrodePotential:
elementsaregivenbelow.
Understandardconditions,thestandardelectrodepotential
3dseries:[Ar]3d1-104S1-2
occursinanelectrochemicalcellsaythetemperature=298K,
4dseries:[Kr]4d1-105S0-2
pressure=1atm,concentration=1M.Thesymbol‘Eocell’ 5dseries:[Xe]5d1-106S2
representsthestandardelectrodepotentialofacell. 6dseries:[Rn]6d1-107S2
OxidationandReduction: AbnormalElectronicConfigurationofChromiumAndCopper
AccordingtoClassicalorearlierconceptoxidationisa amongdBlockElements
processwhichinvolvestheadditionofoxygenorany Chromium(24Cr)haselectronicconfiguration
electronegativeelementortheremovalofhydrogenorany (Expected):[Ar]3d44S2
electropositiveelement. (Observed):[Ar]3d54s1
Copper(29Cu)haselectronicconfiguration
Accordingtoelectronicconceptoxidationisdefinedasthe (Expected):[Ar]3d94s1
processinwhichanatomorionlosesoneormoreelectrons. (Observed):[Ar]3d104s1
, FourTransitionseries
Explanation 1. 3d-Transitionseries. Transitionelementswithan
due to more stability of half –filled and atomicnumber21(Sc)to30(Zn)andwithan
incomplete3dorbitalarecalledthefirstseriesof
completely filled orbital. mutations.
PhysicalProperties
Thetransitionmetalsarehardandtough.Theyhavelow
volatilitybutZn,CdandHgareanexception.
Theyhavehighmeltingandboilingpointsduetothegreater
quantityofelectronsfrom(n-1)dalongwiththenselectrons
metallic
2. 4d-Transitionseries. Itcontainselementswithan
atomicnumber39(Y)to48(Cd)andhasanincomplete
4dorbital.Itiscalledthesecondversionoftheversion.
Metalspossessinghighboilingpointarenobleintheir
Themetalsbelongingtosecondandthirdserieshavegreater
enthalpiesofatomisationthantheelementsbelongingtofirst
series.
3. 5d-Transitionseries. Transitionelementswith
atomicnumbers57(La),72(Hf)to80(Hg)andwithan
incomplete orbital 5d are called the third
transformationseries.
