1. SS CI 11.5 The d block1 The d block: The d block consists of three horizontal series in periods 4, 5 & 6The d block consists of three horizontal series in periods 4, 5 & 6 –10 elements in each series –Chemistry is “different” from other elements –Special electronic configurations important Differences within a group in the d block are less sharp than in s & p blockDifferences within a group in the d block are less sharp than in s & p block Similarities across a period are greaterSimilarities across a period are greater

2. SS CI 11.5 The d block2 Electronic Configuration Across the 1 st row of the d block (Sc to Zn) each element –has 1 more electron and 1 more proton –Each “additional” electron enters the 3d sub-shell –The core configuration for all the period 4 transition elements is that of Ar 1s 2 2s 2 2p 6 3s 2 3p 6

3. SS CI 11.5 The d block3 1s 2s 3s 4s 2p 3p 3d Energy Ar 1s 2 2s 2 2p 6 3s 2 3p 6 4p

4. SS CI 11.5 The d block4 1s 2s 3s 4s 2p 3p 3d Energy Sc 1s 2 2s 2 2p 6 3s 2 3p 6 3d 1 4s 2 4p

5. SS CI 11.5 The d block5 Electronic Arrangement ElementZ3d4s Sc21[Ar] Ti22[Ar] V23[Ar] Cr24[Ar] Mn25[Ar] Fe26[Ar] Co27[Ar] Ni28[Ar] Cu29[Ar] Zn30[Ar]

6. SS CI 11.5 The d block6 Chromium and Copper Cr and Cu don’t fit the pattern of building up the 3d sub-shell, why? –In the ground state electrons are always arranged to give lowest total energy –Electrons are negatively charged and repel each other –Lower total energy is obtained with e - singly in orbitals rather than if they are paired in an orbital –Energies of 3d and 4s orbitals very close together in Period 4

7. SS CI 11.5 The d block7 Chromium and Copper At Cr –Orbital energies such that putting one e - into each 3d and 4s orbital gives lower energy than having 2 e - in the 4s orbital At Cu –Putting 2 e - into the 4s orbital would give a higher energy than filling the 3d orbitals

8. SS CI 11.5 The d block8 1s 2s 3s 4s 2p 3p 3d Energy Cr 1s 2 2s 2 2p 6 3s 2 3p 6 3d 5 4s 1 4p

9. SS CI 11.5 The d block9 1s 2s 3s 4s 2p 3p 3d Energy Cu 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 1 4p

10. SS CI 11.5 The d block10

11. SS CI 11.5 The d block11

12. SS CI 11.5 The d block12 What is a transition metal? Transition metals [TM’s] have characteristic properties –e.g. coloured compounds, variable oxidation states These are due to presence of an inner incomplete d sub-shell Electrons from both inner d sub-shell and outer s sub-shell can be involved in compound formation

13. SS CI 11.5 The d block13 What is a transition metal? Not all d block elements have incomplete d sub-shells –e.g. Zn has e.c. of [Ar]3d 10 4s 2, the Zn 2+ ion ([Ar] 3d 10 ) is not a typical TM ion –Similarly Sc forms Sc 3+ which has the stable e.c of Ar. Sc 3+ has no 3d electrons Note that when d block elements form ions the s electrons are lost first

14. SS CI 11.5 The d block14 What are TM’s like? TM’s are metals They are similar to each other but different from s block metals eg Na and Mg Properties of TM’s –Dense metals –Have high T m and T b –Tend to be hard and durable –Have high tensile strength –Have good mechanical properties

15. SS CI 11.5 The d block15 TM Chemical Properties Typical chemical properties of the TM’s are –Formation of compounds in a variety of oxidation states –Catalytic activity of the elements and their compounds –Strong tendency to form complexes –Formation of coloured compounds

16. SS CI 11.5 The d block16 Oxidation States of TM’s In the following table –Most important OS’s in boxes –OS = +1 only important for Cu –OS = +2, where 4s e - lost shown by all except for Sc and Ti –OS = +3, shown by all except Zn

17. SS CI 11.5 The d block17 Oxidation States of TM’s ScTiVCrMnFeCoNiCuZn +1 +2 +3 +4 +5 +6 +7

18. SS CI 11.5 The d block18 Oxidation States of TM’s No of OS’s shown by an element increases from Sc to Mn –In each of these elements highest OS is equal to no. of 3d and 4s e - After Mn decrease in no. of OS’s shown by an element –Highest OS shown becomes lower and less stable –Seems increasing nuclear charge binds 3d e - more strongly, hence harder to remove

19. SS CI 11.5 The d block19 Oxidation States of TM’s In general –Lower OS’s found in simple ionic compounds E.g. compounds containing Cr 3+, Mn 2+, Fe 3+, Cu 2+ ions –TM’s in higher OS’s usually covalently bound to electronegative element such as O or F E.g VO 3 -, vanadate(V) ion; MnO 4 -, manganate(VII) ion are not formedSimple ions with high OS’s such as V 5+ & Mn 7+ are not formed

20. SS CI 11.5 The d block20 Stability of OS’s Change from one OS to another is a redox reaction Relative stability of different OS’s can be predicted by looking at Standard Electrode Potentials –E  values

21. SS CI 11.5 The d block21 Stability of OS’s General trends –Higher OS’s become less stable relative to lower ones on moving from left to right across the series –Compounds containing TM’s in high OS’s tend to be oxidising agents e.g MnO 4 - –Compounds with TM’s in low OS’s are often reducing agents e.g V 2+ & Fe 2+

22. SS CI 11.5 The d block22 Catalytic Activity TM’s and their compounds effective and important catalysts –Industrially and biologically!! The “people in the know” believe –catalysts provide reaction pathway with lower E A than uncatalysed reaction (see CI 10.5) Once again, –availability of 3d and 4s e - –ability to change OS –among factors which make TM’s such good catalysts

23. SS CI 11.5 The d block23 Heterogeneous Catalysis Catalyst in different phase from reactants –Usually means solid TM catalyst with reactants in liquid or gas phases TM’s can –use the 3d and 4s e - of atoms on metal surface to from weak bonds to the reactants. –Once reaction has occurred on TM surface, these bonds can break to release products Important example is hydrogenation of alkenes using Ni or Pt catalyst

24. SS CI 11.5 The d block24 Heterogeneous Catalysis

25. SS CI 11.5 The d block25 Homogeneous Catalysis Catalyst in same phase as reactants –Usually means reaction takes place in aqueous phase –Catalyst aqueous TM ion Usually involves intermediate compound –TM ion forming intermediate compound with ome or more of the reactants –Intermediate then breaks down to form products

26. SS CI 11.5 The d block26

27. SS CI 11.5 The d block27 Ligands Are neutral molecules or anions which contain a non-bonding pair of electrons Examples: H 2 0, NH 3, CN -, Cl -

28. SS CI 11.5 The d block28 Formation of complex ions Dative covalent bonding is where one species donates both electrons to the bond formed These bonds are usually represented as dotted lines or arrows pointing to the central atom The number of lone pairs bonded to the metal ion is known as the coordination number

29. SS CI 11.5 The d block29 [Ag(NH 3 ) 2 ] + Co-ordination number 2 Shape: linear

30. SS CI 11.5 The d block30 [CuCl 4 ] 2- Co-ordination number = 4 Shape tetrahedral

31. SS CI 11.5 The d block31 [Fe(CN) 6 ] 3- Co-ordination number = 6 Shape: octahedral

32. SS CI 11.5 The d block32 Coloured Complexes In a free ion, the five d orbitals are of equal energy, however when they form complexes the d orbitals are split into 2 distinctive energy levels. The energy difference corresponds to the energy of a particular wavelength of visible light

33. SS CI 11.5 The d block33 Coloured complexes When electrons absorb this energy they move from the lower to the upper d energy level The rest of the visible light is reflected, which is the colour we see

34. SS CI 11.5 The d block34 So what d block complexes will not be coloured ? Ones with no d electrons eg…… Sc 3+, Ti 4+..or those for which the d shell is full so electrons cannot move. Eg… Zn 2+, Cu +

35. SS CI 11.5 The d block35 3d orbitals in Ni 2+ complexes Absorbs red appears green Absorbs orange appears blue Ni(H 2 O) 6 2+ Ni(NH 3 ) 6 2+

36. SS CI 11.5 The d block36 Oxides Ionic Ionic with Covalent character AmphotericAl 2 O 3 Covalent Acidic CO 2 SO 2 NO 2 Basic Na 2 O

37. SS CI 11.5 The d block37 Ionic Oxides O 2- + H 2 O  2OH - Na 2 O(s) + H 2 O(l)  2NaOH(aq) Li 2 O(s) + H 2 O(l)  2LiOH(aq) MgO(s) + H 2 O(l)  Mg(OH) 2 (s)

38. SS CI 11.5 The d block38 Amphoteric Oxides Al 2 O 3 + 6H +  2Al 3+ + 3H 2 O Al 2 O 3 + 2OH - + 3H 2 O  2[Al(OH) 4 ] - BeO + 2H +  Be 2+ + H 2 O BeO + 2OH - + H 2 O  [Be(OH) 4 ] 2-

39. SS CI 11.5 The d block39 Covalent Oxides O=X  + :O-H H [O-X-OH] - + H + Mechanism of the Hydrolytic behaviour of covalent oxides: CO 2 + H 2 O  H 2 CO 3  H + + HCO 3 - SO 2 + H 2 O  H 2 SO 3  H + + HSO 3 - 2NO 2 + H 2 O  HNO 3 + HNO 2

40. SS CI 11.5 The d block40 Covalent Oxides P 4 O 6 and P 4 O 10 : P 4 O 6 (s) + 6H 2 O(l), cold  4H 3 PO 3 (aq) P 4 O 6 (s) + 6H 2 O(l), hot  3H 3 PO 4 (aq) + PH 3 (g) P 4 O 10 (s) + 6H 2 O(l)  4H 3 PO 4 (aq) The actual reactions are complicated. The products formed depend on the amount of water present and the conditions of reaction.

41. SS CI 11.5 The d block41 Covalent Oxides Group VIIA: F 2 O, Cl 2 O and Cl 2 O 7 F 2 O(g) + H 2 O(l)  2HF(aq) + O 2 (g) Cl 2 O(g) + H 2 O(l)  2HOCl(aq) Cl 2 O 7 (l) + H 2 O(l)  2HClO 4 (aq) Cl O O O O O O O Cl 2 O 7 (g)/(l) Cl O O O O O O O + - Cl 2 O 7 (s)

42. SS CI 11.5 The d block42 Chlorides LiCl NaCl MgCl 2 Ionic AlCl 3 BeCl 2 Intermediate with covalent character BCl 3 CCl 4 SiCl 4 NCl 3 PCl 5 PCl 3 OCl 2 S 2 Cl 2 SCl 2 ClF Cl 2 Covalent

43. SS CI 11.5 The d block43 Ionic chlorides Group IA –LiCl, NaCl are not hydrolysed in aqueous solution, neutral solution formed when dissolved. NaCl (s)  Na + (aq) + Cl - (aq), LiCl (s)  Li + (aq) + Cl - (aq) Group IIA –MgCl 2 is not hydrolysed. –Hydrated crystals undergoes hydrolysis when heated. MgCl 2.6H 2 O  MgCl(OH) + 5H 2 O + HCl

44. SS CI 11.5 The d block44 Intermediate chlorides BeCl 2 and AlCl 3 : Be 2+ and Al 3+ High charge/size ratio, strong polarizing power, cation hydrolysis. Be 2+ :O H H :OH 2 Be(OH) 2 + HClBeCl 2 + 2H 2 O AlCl 3 + 3H 2 O  Al(OH) 3 + 3HCl

45. SS CI 11.5 The d block45 Covalent chlorides Group IIIA BCl 3 Cl B+B+ :OH 2 Due to presence of vacant orbital and the polar B-Cl bond. BCl 3 reacts vigorously with water to give boric acid, H 3 BO 3 and HCl. BCl 3 (l) + 3H 2 O(l)  H 3 BO 3 (aq) + 3HCl(aq)

46. SS CI 11.5 The d block46 Covalent chlorides Group 4A : CCl 4 and SiCl 4 Cl Si Cl C CCl 4 does not hydrolyzed by water SiCl 4 hydrolyzes. SiCl 4 (g) + 4H 2 O(l)  SiO 2.2H 2 O(s) + 4HCl(aq)

47. SS CI 11.5 The d block47 Covalent chlorides Group VA: NCl 3 NCl 3 (l) + 3H 2 O(l)  NH 3 (aq) + 3HOCl(aq) chloric(I) acid N does not have low-lying vacant orbital, it hydrolyses through the donation of lone pair electron of N atom to the H atom of water molecule. :O H H :N  - Cl 3

48. SS CI 11.5 The d block48 Covalent chlorides Group VA: PCl 3 and PCl 5 PCl 3 (l) + 3H 2 O(l)  H 3 PO 3 (aq) + 3HCl(aq) PCl 5 (s) + 4H 2 O(l)  H 3 PO 4 (aq) + 5HCl(aq) P is less electronegative than Cl. PCl 3 and PCl 5 hydrolyze by accepting the electron pair from water molecule.

49. SS CI 11.5 The d block49 Covalent chlorides Group VI: SCl 2, S 2 Cl 2 SCl 2 (g) + H 2 O(l)  HSCl(aq) + HOCl(aq) S 2 Cl 2 (l) + 2H 2 O(l)  H 2 S(g) + SO 2 (g) + 2HCl(aq) Group VII: FCl, Cl 2 FCl(g) + H 2 O(l)  HF(aq) + HOCl(aq) Cl 2 (g) + H 2 O(l)  HCl(aq) + HOCl(aq)

50. SS CI 11.5 The d block50