dandfblock-151025055616-lva1-app6891.pdf

The description of the d and f block and the properties and their reactions

1. d –AND f –BLOCK ELEMENTS
TINTO JOHNS M. Sc., M. Ed

3. •Thed-blockoftheperiodictablecontainsthe
elementsofthegroups3-12inwhichthed
orbitalsareprogressivelyfilledineachofthefour
longperiods.
•Theelementsconstitutingthef-blockarethose
inwhichthe4fand5forbitalsareprogressively
filledinthelattertwolongperiods.
•Therearemainlythreeseriesofthetransition
metals,3dseries(SctoZn),4dseries(YtoCd)
and5dseries(LatoHg,omittingCetoLu).The
fourth6dserieswhichbeginswithAcisstill
incomplete.Thetwoseriesoftheinner
transitionmetals,(4fand5f)areknownas
lanthanoidsandactinoidsrespectively.

5. •Atransitionelementisdefinedas
theonewhichhasincompletely
filleddorbitalsinitsgroundstate
orinanyoneofitsoxidationstates.
•Zinc, cadmium and mercury of group 12 have
full d
10
configuration in their ground state as
well as in their common oxidation states and
hence, are not regarded as transition metals

6. Position in the Position in the Periodic Table Periodic
Table
•The d–block occupies the large middle section
flanked by s–and p–blocks in the periodic table.
•Electronic Configurations of the d-Block of the d-
Block Elements
•General the electronic configuration (n-1)d
1–10
ns
1–2
.
•Halfandcompletelyfilledsetsoforbitalsare
relativelymorestable.Aconsequenceofthisfactor
isreflectedintheelectronicconfigurationsofCrand
Cuinthe3dseries.ConsiderthecaseofCr,for
example,whichhas3d
5
4s
1
insteadof3d
4
4s
2
.

7. Physical properties
•Thetransitionmetals(withtheexceptionof
Zn,CdandHg)areverymuchhardandhave
lowvolatility.Theirmeltingandboilingpoints
arehigh.

8. MELTING POINT AND BOILING POINT
•HighM.PandB.P-Duetostrongmetallicbond
andthepresenceofhalffilledd-orbitals
•Involvementofgreaternumberofelectrons
from(n-1)dinadditiontothenselectronsin
theinteratomicmetallicbonding.
•Because of stronger interatomicbonding
High enthalpy of atomisationtransition
elements have high M.P and B.P

9. •Inmovingalongtheperiodfromlefttoright,
theM.PofthesemetalsfirstINCREASESto
MAXIMUMandtheDECREASESregularly
towardstheendoftheperiod.

10. •melting points of these metals rise to a maximum at
d
5
except for anomalous values of Mnand Tcand fall
regularly as the atomic number increases.
TRENDS OF M.P OF 3-d , 4-d AND 5-d TRANSITION
METALS
•Thestrengthofinteratomicbondsintransition
elementsisroughlyrelatedtothenumberofhalf
filledd-orbitals
•Inthebeginningtheno.ofhalffilledd-orbitals
increasestillthemiddleoftheperiodcausing
increaseinstrengthofinterparticlebondsBut
thereafterthepairingofelectronsind–orbitals
occursandtheno.ofhalffilledorbitalsdecreases,
whichalsocausedecreaseinM.P

11. Trends in enthalpies of atomization of transition elements
1.Greaterthenumberofvalenceelectrons,strongerthe
interatomicattraction,hencestrongerbonding
betweenatomsresultinginhigherenthalpiesof
atomization.
2.metalsofthesecondandthirdserieshavegreater
enthalpiesofatomizationthanthecorresponding
elementsofthefirstseries

12. Atomic and ionic radii
•TheAtomic/ionicradiifirstDECREASEStillthe
middle,becomesalmostconstantandthen
INCREASEStowardstheendoftheperiod.
•Newelectronentersadorbitaleachtimethe
nuclearchargeincreasesbyunity,Butthe
shieldingeffectofadelectronisnotthat
effective,hencethenetelectrostaticattraction
betweenthenuclearchargeandtheoutermost
electronincreasesandtheionicradius
decreases

13. •Howevertheincreasednuclearchargeispartly
cancelledbytheincreasedscreeningeffectof
electronsinthed–orbitalsofpenultimateshell.
•When the increased nuclear charge and increased
Screening effect balance each other, the atomic
radii becomes almost constant.
•Increase in atomic radii towards the end may be
attributed to the electron –electron repulsion.
•In fact the pairing of electrons in d –orbitals
occurs after d
5
configuration.
•Therepulsiveinteractionbetweenthepaired
electroncausesIncreaseinAtomic/ionicradii

15. •Thereisincreasefromthefirst(3d)tothe
second(4d)seriesoftheelements.
•Buttheradiiofthethird(5d)seriesare
virtuallythesameas4d
•Thisisduetotheinterventionofthe4forbital
whichmustbefilledbeforethe5dseriesof
elementsbegin.
•Thereisasteadydecreaseinatomicradiifrom
Laduetothepoorshieldingofinnercore
electrons(4f)isknownlanthanoidcontraction.

16. Why do the transition elements exhibit higher
enthalpies of atomisation?
•Becauseoflargenumberofunpairedelectrons
intheiratomstheyhavestrongerinteratomic
interactionandhencestrongerbonding
betweenatomsresultinginhigherenthalpies
ofatomisation.

17. IONISATION ENTHALPIES
•Duetoanincreaseinnuclearchargethereisan
increaseinionisationenthalpyalongeachseries
ofthetransitionelementsfromlefttoright.
•Ionisationenthalpiesgivesomeguidance
concerningtherelativestabilitiesofoxidation
states.
•Althoughthefirstionisationenthalpy,ingeneral,
increases,themagnitudeoftheincreaseinthe
secondandthirdionisationenthalpiesforthe
successiveelements,ingeneral,ismuchhigher.
•MostlyIE1<IE2<IE3ineachgroup

19. •TheincreaseinIEisprimarilyduetoincrease
innuclearcharge.Asthetransitionelements
involvethegradualfillingof(n-1)dorbitals,
theeffectofincreaseinnuclearchargeis
partlycancelledbytheincreaseinscreening
effect.
•Consequently, the increase in I.E along the
periods of d –block elements is very small.

20. Relation between I.E and Stability of a
metal in a given oxdnstate
•WiththehelpofI.E,wecanpredictwhichof
thetwometalsinagivenoxdnstateis
thermodynamicallymorestable.
Eg
•When a metal M (0) is converted into M(II), the
energy required is equal to I
1 + I
2
Similarly M (IV) = I
1 + I
2+ I
3+ I
4

21. •Ni (0) Ni (II) I
1 + I
2 =2.49 x 10
3
kJ mol
-1
•Pt (0) Pt (II) I
1 + I
2 =2.66 x 10
3
kJ mol
-1
•Ni (0) Ni (IV)
I
1 + I
2+ I
3 + I
4 =11.299 x 10
3
kJ mol
-1
•Pt (0) Pt (IV)
I
1 + I
2+ I
3 + I
4 =9.36 x 10
3
kJ mol
-1
I
1 + I
2 for Ni (II) is less than I
1 + I
2for Pt (II). So Ni
(II) is more stable
Similarly Pt (IV) is more stable

22. OXIDATION STATES
+3
•Oneofthenotablefeaturesofatransition
elementisthegreatvarietyofoxidationstatesit
mayshowinitscompounds
•Stabilityofaparticularoxdnstatedependsup
onnatureoftheelementwithwhichthe
transitionmetalsformthecompound

23. •Theelementswhichgivethegreatestnumber
ofoxidationstatesoccurinornearthemiddle
oftheseries.Manganese,forexample,exhibits
alltheoxidationstatesfrom+2to+7.
•Elementsinthebeginningoftheseriesexhibit
feweroxidationstate(havesmallno.of
electronsinwhichtheyloseorcontributefor
sharing).
•Elementsattheendoftheseriesshowsfewer
oxdnstatesbecausetheyhavetoomany
electronsind–orbitals.Sotheyhavefew
vacantd–orbitalswhichcanbeinvolvedin
bonding.

24. •Loweroxdnstate–Covalentcharacter
•Higheroxdnstate–ionic
•Higheroxdnstatesaremorestableforheavier
members.
Eg:ingroupVI,Mo(VI)andW(VI)aremorestable
thanCr(VI).SoCr(VI)actasstrongoxidizingagent.
•Thehighestoxdnstate-+8(Rutheniumand
Osmium).
•Lowoxidationstatesarefoundwhenacomplex
compoundhasligandscapableofπ-acceptor
characterinadditiontotheσ-bonding.Forexample,
inNi(CO)
4andFe(CO)
5,theoxidationstateofnickel
andironiszero.

25. Trends in Stability of Higher Oxidation
States
•Stability –compounds with F and Oxygen
•TheabilityofFluorinetostabilizethehighest
oxidationstateisduetoeitherhighlattice
energyasincaseofCoF
3orhighbond
enthalpyasincaseofVF
5andCrF
6.
•TheabilityofOxygentostabilizethehighest
oxidationstateisduetoitsabilitytoform
multiplebondswithmetals.

26. Stablehalidesoffirsttransitionelements
Oxdn
no.
4 5 6 7 8 9 10 11 12
+6 Cr F
6
+5 VF
5Cr F
5
+4TiX
4VX
4
I
CrX
4MNf
4
+3TiX
3VX
3CrX
3MnF
3Fe X
3Co F
3
+2TiX
2
III
VX
2
I
CrX
2MnX
2Fe X
2Co X
2Ni X
2Cu X
2
II
ZnX
2
+1 Cu X
III
X = F to I, X
II
= F,
X
I
= F to Br , X
III
= Clto I

27. •Thehighestoxidationnumbersareachievedin
TiX
4(tetrahalides),VF
5andCrF
6.The+7state
forMnisnotrepresentedinsimplehalidesbut
MnO
3Fisknown,andbeyondMn,nometalhas
atrihalideexceptFeX
3andCoF
3.
•AlthoughV(V)isrepresentedonlybyVF
5,the
otherhalides,however,undergohydrolysisto
giveoxohalides,VOX
3.Anotherfeatureof
fluoridesistheirinstabilityinthelowoxidation
statese.g.,VX
2(X=CI,BrorI)

28. •AllCu(II)halidesareknownexcepttheiodide.
Inthiscase,Cu
2+
oxidisesI
–
toI
2
:
2Cu
2+
+ 4I
-
→ Cu
2I
2(s)+ I
2
•However,manycopper(I)compoundsare
unstableinaqueoussolutionandundergo
disproportionation.
2Cu
2+
→Cu
2+
+Cu
•ThestabilityofCu
2+
(aq)ratherthanCu
+
(aq)is
duetothemuchmorenegativeΔ
hydH
0
ofCu
2+
(aq)thanCu
+
,whichmorethancompensates
forthesecondionisationenthalpyofCu.

29. •Transitionmetalsalsoexhibitsthehighest
OxdnstateintheirOxides.
•TheabilityofOxygentostabilizehigher
oxidationstatesaremuchhigherthan
Fluorine..
•ThehighestOxdnstatewithFluorinebyMnis
+4inMnF
4whileitis+7inMn
2O
7.
•OxygenhastheabilitytoformMultiplebonds
withMetalatom.
The oxides of 3 –d transition elements are
given below :

30. Ox
dn
No
3 4 5 6 7 8 9 101112
+7 Mn
2O
7
+6 CrO
3
+5 V
2O
5 MnO
2
+4 TiO
2V
2O
4CrO
2Mn
2O
3Fe
2O
3
+3Sc
2O
3Ti
2O
3V
2O
3
Cr
2O
3Mn
3O
4Fe
3O
4Co
3O
4
+2 TiOVOCrOMnO FeOCoONiOCuOZnO
+1 Cu
2O

31. •Thehighestoxidationnumberintheoxides
coincideswiththegroupnumberandis
attainedinSc
2O
3toMn
2O
7.
•BeyondGroup7,nohigheroxidesofFeabove
Fe
2O
3,areknown,althoughferrates(VI)
(FeO4)
2–
,areformedinalkalinemediabutthey
readilydecomposetoFe
2O
3andO
2.
•Besidestheoxides,oxocationsstabiliseV(v)as
VO
2
+
,V(IV)asVO
2+
andTi(IV)asTiO
2+.

32. STANDARD ELECTRODE POTENTIAL
•ELECTRODEPOTENTIALSARETHE
MEASUREOFTHEVALUEOFTOTAL
ENTHALPYCHANGE.
•ElectrodePotentialsvaluedepends
enthalpyofatomizationΔHa&hydration
ΔH
hyd
•LowerthestdE.P(E
o
red),themorestable
istheoxdnstateofthemetalinaqueous
state.

34. The E0(M
2+/M) value for copper is positive (+0.34V) :
high ΔHaand low ΔH hyd). ---GREATER AMNT OF
ENERGY REQUIRED TO TRANSFORM CuINTO Cu
2+

35. •Dueto+veE
o
,Cudoesnotliberate
hydrogenfromacids.
•ThegeneraltrendtowardslessnegativeE
o
valuesacrosstheseriesisrelatedtothe
generalincreaseinthesumofthefirst
andsecondionisationenthalpies.
•ItisinterestingtonotethatthevalueofE
o
forMn,NiandZnaremorenegativethan
expectedfromthetrend.

36. •The stability of the half-filled d sub-shell in Mn
2+
and the completely filled d
10
configuration in Zn
2+
are related to their E
o
values, whereas E
o
for Ni is
related to the highest negativeΔ
hydH
o
.
•ThelowvalueforScreflectsthestabilityofSc
3+
whichhasanoblegasconfiguration.Thehighest
valueforZnisduetotheremovalofanelectron
fromthestabled
10
configurationofZn
2+.
The
comparativelyhighvalueforMnshowsthat
Mn
2+
(d
5
)isparticularlystable,whereas
comparativelylowvalueforFeshowstheextra
stabilityofFe
3+
(d
5
).

37. CHEMICAL REACTIVITY
•Transitionmetalsvarywidelyintheirchemical
reactivity.Manyofthemaresufficiently
electropositivetodissolveinmineralacids,
althoughafeware‘noble’—thatis,theyare
unaffectedbysimpleacids.
•Themetalsofthefirstserieswiththeexception
ofcopperarerelativelymorereactiveandare
oxidisedby1MH
+
,thoughtheactualrateat
whichthesemetalsreactwithoxidisingagents
likehydrogenion(H
+
)issometimesslow.

38. •TheE
O
valuesforM
2+/
Mindicateadecreasing
tendencytoformdivalentcationsacrossthe
series.
•ThisgeneraltrendtowardslessnegativeE
O
valuesisrelatedtotheincreaseinthesumof
thefirstandsecondionisationenthalpies.
•ItisinterestingtonotethattheE
O
valuesfor
Mn,NiandZnaremorenegativethan
expectedfromthegeneraltrend.

39. •E
O
valuesfortheredoxcoupleM3+/M2+
showsthatMn
3+
andCo
3+
ionsarethe
strongestoxidisingagentsinaqueous
solutions.TheionsTi
2+,
V
2+
andCr
2+
arestrong
reducingagentsandwillliberatehydrogen
fromadiluteacid,
e.g.,
•2 Cr
2+
(aq) + 2 H
+
(aq) → 2 Cr
3+
(aq) + H
2(g)

40. MAGNETIC PROPERTIES
•Substanceswhichcontainspecies
(Atoms/ions/molecules)withunpared
electronsintheirorbitals–PARAMAGNETIC.
•PARAMAGNETICSUBSTANCESareweakly
attractedbythemagneticfield.
•StronglyattractedcalledFERROMAGNETIC.
•Substanceswhichdonotcontainanyunpaired
electronsandarerepelledbymagneticfield-
DIAMAGNETIC.

41. •Transition metals usually contains unpaired
electrons –so it is paramagnetic.
•Paramagneticbehaviorincreaseswith
increaseinunpairedelectron.
•Paramagnetismexpressedintermsof
Magneticmoment.,itisrelatedtono.of
unpairedelectrons.
•The magnetic moments calculated from the
‘spin-only’ formula and those derived
experimentally.
Magnetic moment µ = √ n(n+2) BM

42. n-no.ofunpairedelectrons
BM–Bohrmagnetone(unitofM.M)
BM=9.27x10
-21
erg/gauss
•Singleunpairedelectronhasamagnetic
momentof1.73Bohrmagnetons(BM).
•magneticmomentofanelectronisduetoits
spinangularmomentumandorbitalangular
momentum

44. Formation of ColouredIons
•Whenanelectronfromalowerenergyd
orbitalisexcitedtoahigherenergydorbital,
theenergyofexcitationcorrespondstothe
frequencyoflightabsorbed.
•Thisfrequencygenerallyliesinthevisible
region.Thecolourobservedcorrespondsto
thecomplementarycolourofthelight
absorbed.
•Thefrequencyofthelightabsorbedis
determinedbythenatureoftheligand.

45. •Zn
2+
/ Cd
2+
-all d orbitalsare fully filled
•Ti
4+
-all d orbitalsare vacant
so, no d –d transition occurs. Therefore they
do not absorb radiations. So they are
colorless.

46. FormationofComplex Compounds
•Metal ions bind a number of anions or neutral
molecules giving complex
[Fe(CN)
6]
3–
, [Fe(CN)
6]
4–
, [Cu(NH
3)
4]
2+
and
[PtCl
4]
2–
.
This is due to the
•Comparatively smaller sizes of the metal ions,
•Their high ionic charges and
•The availability of d orbitals for bond formation.

47. Formation of Interstitial Compounds
•When small atoms like H, C or N are trapped
inside the crystal lattices of metals
•They are usually non stoichiometric
•example, TiC, Mn
4N, Fe
3H, VH
0.56and TiH
1.7
(i)Theyhavehighmeltingpoints,higherthanthoseof
puremetals.
(ii)Theyareveryhard,someboridesapproach
diamondinhardness.
(iii)Theyretainmetallicconductivity.
(iv)Theyarechemicallyinert.

48. Alloy Formation
•Because of similar radii and other characteristics
of transition metals,
•The alloys so formed are hard and have often
high melting points.
•ferrous alloys: chromium, vanadium, tungsten,
molybdenum and manganese are used for the
production of a variety of steels and stainless
steel.
•Alloys of transition metals with non transition
metals such as brass (copper-zinc) and bronze
(copper-tin),

49. CATALYTIC ACTIVITY
•The transition metals and their compounds
are known for their catalytic activity.
•This activity is ascribed to their ability to
adopt multiple oxidation states and to form
complexes.

50. DISPROPORTIONATION
•Whenaparticularoxidationstatebecomesless
stablerelativetootheroxidationstates,one
lower,onehigher,itissaidtoundergo
disproportionation.Forexample,manganese(VI)
becomesunstablerelativetomanganese(VII)and
manganese(IV)inacidicsolution.
3 Mn
VI
O4
2–
+ 4 H
+
→ 2 Mn
VII
O
–
4 + Mn
IV
O
2+ 2H
2O

51. Oxides and Oxoanionsof Metals
•The elements of first transition series form
variety of oxides of different oxidation states
having general formula MO, M
2O
3, M
3O
6,
MO
2, MO
3.
•Theses oxides are generally formed by heating
the metal with oxygen at high temperature.

52. Sc –Sc
2O
3Basic
Ti –TiOBasic, Ti
2O
2Basic, TiO
2Amphoteric
V –VO Basic, V
2O
3Basic, VO
2Ampho, V
2O
5Acidic
Cr –CrOBasic, Cr
2O
3Ampho, CrO
2Ampho,
CrO
3Acidic
Mn–MnObasic, Mn
2O
3Basic, Mn
3O
4Ampho,
MnO
2 Ampho, Mn
2O
7Acidic
Fe –FeOBasic,Fe
2O
3Amph, Fe
3O
4Basic
Co –CoOBasic
Ni –NiOBasic
Cu –Cu
2O Basic, CuOAmpho
Zn –ZnOAmpho

53. •In general
lower oxidation state metal –BASIC
Higher oxidation state metal –ACIDIC
Intermediate oxidation state -AMPHOTERIC
•Example
MnO(+2)basic,Mn
2O
3(+3)Basic,Mn
3O
4(+
8/3)Ampho,
MnO
2(+4)Ampho,Mn
2O
7(+7)Acidic

54. •Thehighestoxidationnumberintheoxides
coincideswiththegroupnumberandis
attainedinSc
2O
3toMn
2O
7.
•BeyondGroup7,nohigheroxidesofFe
aboveFe
2O
3,areknown,althoughferrates
(VI)(FeO4)
2–
,areformedinalkalinemedia
buttheyreadilydecomposetoFe
2O
3and
O
2.
•Besidestheoxides,oxocationsstabilise
V(v)asVO
2
+
,V(IV)asVO
2+
andTi(IV)as
TiO
2+.

55. •As the oxidation number of a metal increases,
ionic character decreases. In the case of Mn,
Mn
2O
7is a covalent green oil. Even CrO
3and
V
2O
5have low melting points. In these higher
oxides, the acidic character is predominant.

56. Potassium dichromate K2Cr2O7
STEP1
•Dichromatesaregenerallypreparedfrom
chromatewhichinturnareobtainedbythe
fusionofchromiteore(FeCr2O4)with
sodiumorpotassiumcarbonateinfree
accessofair.Thereactionwithsodium
carbonateoccursasfollows:
4 FeCr
2O
4+ 8 Na
2CO
3+ 7 O
2→ 8 Na
2CrO
4+
2Fe
2O
3+ 8 CO
2

57. STEP2
•Theyellowsolutionofsodiumchromateis
filteredandacidifiedwithsulphuricacidtogivea
solutionfromwhichorangesodiumdichromate,
Na
2Cr
2O
7.2H
2Ocanbecrystallised.
2Na
2CrO
4+ H
2SO
4 → Na
2Cr
2O
7+ Na
2SO
4+ H
2O
STEP3
ConversionofSodiumdichromateintoPotassium
dichromate
Na
2Cr
2O
7+ 2 KCl → K
2Cr
2O
7+ 2 NaCl

58. •The oxidation state of chromiuminchromate
and dichromate is the same.
2 CrO
4
2–
+ 2H
+
→ Cr
2O
7
2–
+ H
2O
Cr
2O
7
2–
+ 2 OH
-
→ 2 CrO
4
2–
+ H
2O
•Thechromateionistetrahedralwhereasthe
dichromateionconsistsoftwotetrahedral
sharingonecornerwithCr–O–Crbondangle
of126°.

59. •Sodium and potassium dichromatesare strong oxidising
agents
Potassium dichromate is used as a primary standard in
volumetric analysis. In acidic solution, its oxidisingaction
can be represented as follows:
Cr
2O
7
2–
+ 14H
+
+ 6e
–
→ 2Cr
3+
+ 7H
2O (EV = 1.33V)

60. •acidified potassium dichromate will oxidise
iodides to iodine, sulphidesto sulphur, tin(II)
to tin(IV) and iron(II) salts to iron(III). The half-
reactions are noted below:
•6 I
–
→ 3I
2+ 6 e
–
;
•3 H
2S → 6H
+
+ 3S + 6e
–
•3 Sn
2+
→ 3Sn
4+
+ 6 e
–
•6 Fe
2+
→ 6Fe
3+
+ 6 e
–
Cr
2O
7
2–
+ 14 H
+
+ 6 Fe
2+
→ 2 Cr
3+
+ 6 Fe
3+
+ 7 H
2O

61. Potassium permanganate KMnO
4
•Potassium permanganate is prepared by fusion
of MnO
2with an alkali metal hydroxide and an
oxidisingagent like KNO
3. This produces the
dark green K
2MnO
4which disproportionatesin
a neutral or acidic solution to give
permanganate.
2MnO
2+ 4KOH + O
2→ 2K
2MnO
4+ 2H
2O
3MnO
4
2–
+ 4H
+
→ 2MnO
4
–
+ MnO
2+ 2H
2O

62. Themanganateandpermanganateionsare
tetrahedral;thegreenmanganateis
paramagneticwithoneunpairedelectronbutthe
permanganateisdiamagnetic.

63. THE INNER TRANSITION ELEMENTS (
f-BLOCK)

64. •Theelementsinwhichtheadditional
electronsenters(n-2)forbitalsarecalledinner
transitionelements.Thevalenceshell
electronicconfigurationoftheseelementscan
berepresentedas(n–2)f
0-14
(n–1)d
0-1
ns
2
.
•4finnertransitionmetalsareknownas
lanthanidesbecausetheycomeimmediately
afterlanthanumand5finnertransitionmetals
areknownasactinoidsbecausetheycome
immediatelyafteractinium.

65. Electronic Configuration
Element name Symbol Z Ln Ln
3+
Radius
Ln
3+
/ pm
Lanthanum La 57 [Xe]6s
2
5d
1
[Xe]4f
0
116
Cerium Ce 58 [Xe]4f
1
6s
2
5d
1
[Xe]4f
1
114
Praesodymium Pr 59 [Xe]4f
3
6s
2
[Xe]4f
2
113
Neodymium Nd 60 [Xe]4f
4
6s
2
[Xe]4f
3
111
Promethium Pm 61 [Xe]4f
5
6s
2
[Xe]4f
4
109
Samarium Sm 62 [Xe]4f
6
6s
2
[Xe]4f
5
108
Europium Eu 63 [Xe]4f
7
6s
2
[Xe]4f
6
107
Gadolinium Eu 64 [Xe]4f
7
6s
2
5d
1
[Xe]4f
7
105
Terbium Tb 65 [Xe] 4f
9
6s
2
[Xe]4f
8
104
Dysprosium Dy 66 [Xe] 4f
10
6s
2
[Xe]4f
9
103
Holmium Ho 67 [Xe] 4f
11
6s
2
[Xe]4f
10
102
Erbium Er 68 [Xe] 4f
12
6s
2
[Xe]4f
11
100
Thulium Tm 69 [Xe] 4f
13
6s
2
[Xe]4f
12
99
Ytterbium Yb 70 [Xe] 4f
14
6s
2
[Xe]4f
13
99
Lutetium Lu 71 [Xe] 4f
14
6s
2
5d
1
[Xe]4f
14
98

66. Atomic and ionic sizes: The Lanthanide
Contraction
•Astheatomicnumberincreases,each
succeedingelementcontainsonemore
electroninthe4forbitalandoneprotonin
thenucleus.The4felectronsareineffectivein
screeningtheouterelectronsfromthe
nucleuscausingimperfectshielding.Asa
result,thereisagradualincreaseinthe
nucleusattractionfortheouterelectrons.
Consequentlygradualdecreaseinsizeoccur.
Thisiscalledlanthanidecontraction.

67. Consequences of L. C
•There is close resemblance between 4d and
5d transition series.
•Ionization energy of 5d transition series is
higher than 3d and 4d transition series.
•Difficulty in separation of lanthanides

68. Ionization Enthalpies
•Fairly low I. E
•Firstionizationenthalpyisaround600kJmol
-1
,
thesecondabout1200kJmol
-1
comparable
withthoseofcalcium.
•DuetolowI.E,lanthanideshavehigh
electropositivecharacter

69. Colouredions
•Manyofthelanthanoidionsarecolouredin
bothsolidandinsolutionduetof–f
transitionsincetheyhavepartiallyfilledf–
orbitals.
•Absorptionbandsarenarrow,probably
becauseoftheexcitationwithinflevel.
•La
3+
andLu
3+
ionsdonotshowanycolour
duetovacantandfullyfilledf-orbitals.

70. Magnetic properties
•Thelanthanoidionsotherthenthef
0
type
(La
3+
andCe
3+
)andthef
14
type(Yb
2+
andLu
3+
)
areallparamagnetic.Theparamagnetismrises
tothemaximuminneodymium.
•Lanthanideshaveveryhighmagnetic
susceptibilitiesduetotheirlargenumbersof
unpairedf-electrons.

71. Oxidation States
•Predominantly +3 oxidation state.
•+3oxidationstateinLa,Gd,Luareespecially
stable(EmptyhalffilledandCompletelyfilledf–
subshellrespectively)
•CeandTbshows+4oxdnstate(Ce
4+
-4f
o
&Tb
4+
4f
7
)
•Occasionally +2 and +4 ions in solution or in solid
compounds are also obtained.
•Thisirregularityarisesmainlyfromtheextra
stabilityofempty,halffilledorfilledfsubshell.

72. •The most stable oxidation state of lanthanides
is +3. Hence the ions in +2 oxidation state tend
to change +3 state by loss of electron acting as
reducing agents whereas those in +4 oxidation
state tend to change to +3 oxidation state by
gain of electron acting as a good oxidising
agent in aqueous solution.
•Why Sm
2+
, Eu
2+
, and Yb
2+
ions in solutions are
good reducing agents but an aqueous solution
of Ce
4+
is a good oxidizing agent?

73. properties
•Silvery white soft metals, tarnish in air rapidly
•Hardness increases with increasing atomic
number, samarium being steel hard.
•Good conductor of heat and electricity.
•Promethium -Radioactive

74. Chemical Properties
•Metal combines with hydrogen when gently
heated in the gas.
•The carbides, Ln
3C, Ln
2C
3and LnC
2are formed
when the metals are heated with carbon.
•They liberate hydrogen from dilute acids and
burn in halogens to form halides.
•They form oxides and hydroxides, M
2O
3and
M(OH)
3, basic like alkaline earth metal oxides
and hydroxides.

75. Ln
W
ith
a
c id
s
With helogensHeated with S
H
eated w
ith N
2
B
u
r
n

w
i
t
h

O
2
2
C 2773 K
W
i
t
h

H

O
Ln S
23
2
3
2
2LnN
LnC
Ln(OH) +H
3LnX
H
Ln O
23

76. The Actinides
•All isotopes are radioactive, with only
232
Th,
235
U,
238
U and
244
Pu having long half-lives.
•Only Thand U occur naturally-both are more
abundant in the earth’s crust than tin.
•The others must be made by nuclear
processes.

77. •Thedominantoxidationstateofactinidesis
+3.Actinidesalsoexhibitanoxidationstateof
+4.Someactinidessuchasuranium,
neptuniumandplutoniumalsoexhibitan
oxidationstateof+6.
•The actinides show actinide contraction (like
lanthanide contraction) due to poor shielding
of the nuclear charge by 5f electrons.
•All the actinides are radioactive. Actinides are
radioactive in nature.

78. ActinoideContraction
•Thesizeofatoms/M
3+
ionsdecreases
regularlyalongactinoidseris.Thesteady
decreaseinionic/atomicradiiwithincreasein
atomicnumberiscalledActinoide
Contraction.
•Thecontractionisgreaterfromelementto
elementinthisseries–duetopoorshielding
effectby5felectron.

79. Electronic configuration
Element name Symbol Z Ln Ln
3+
Radius
Ln
3+
/ pm
Actinium Ac 89 [Rn] 6d
1
7s
2
[Rn]4f
0
111
Thorium Th 90 [Rn]5d
2
7s
2
[Rn]4f
1
Protactinium Pa 91 [Rn]5f
2
6d
1
7s
2
[Rn]4f
2
Uranium U 92 [Rn]5f
3
6d
1
7s
2
[Rn]4f
3
103
Neptunium Np 93 [Rn]5f
4
6d
1
7s
2
[Rn]4f
4
101
Plutonium Pu 94 [Rn]5f
6
7s
2
[Rn]4f
5
100
Americium Am 95 [Rn]5f
7
7s
2
[Rn]4f
6
99
Curium Cm 96 [Rn]5f
7
6d
1
7s
2
[Rn]4f
7
99
Berkelium Bk 97 [Rn]5f
9
7s
2
[Rn]4f
8
98
Californium Cf 98 [Rn]5f
10
7s
2
[Rn]4f
9
98
EinsteiniumEs 99 [Rn]5f
11
7s
2
[Rn]4f
10
Fermium Fm 100 [Rn]5f
12
7s
2
[Rn]4f
11
MendeleviumMd 101 [Rn]5f
13
7s
2
[Rn]4f
12
Nobelium No 102 [Rn]5f
14
7s
2
[Rn]4f
13
Lawrencium Lr 103 [Rn]5f
14
6d
1
7s
2
[Rn]4f
14

80. Magnetic properties
•Paramagnetic behaviour
•Magnetic properties are more complex than
those of lanthanoids.
M.P and B.P
High M.P and B.P
Do not follow regular gradation of M.P or B.P
with increase in atomic number

81. IONISATION ENTHALPY
•Low I.E. so electropositiityis High
COLOUR
•Generally coloured
•Colourdepends up on the number of 5 f
electrons
•The ions containing 5 f
o
and 5 f
7
are
colouress
Eg–
U
3+
(5 f
3
) –Red
NP
3+
(5 f
4
) –Bluish

82. THANK YOU