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D-BLOCK ELEMENTS No. of lectures – 12 Term - 1 1 Paper 2, Unit 1, Chapter 1.

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Presentation on theme: "D-BLOCK ELEMENTS No. of lectures – 12 Term - 1 1 Paper 2, Unit 1, Chapter 1."— Presentation transcript:

1 d-BLOCK ELEMENTS No. of lectures – 12 Term Paper 2, Unit 1, Chapter 1

2 INTRODUCTION OF D-BLOCK ELEMENTS 2 Paper 2, Unit 1, Chapter 1

3 Periodic Table f block transition elements d block transition elements 3 Paper 2, Unit 1, Chapter 1

4 ScTiVCr Mn FeCoNiCuZn YZrNb MoMoTcRuRhPdAgCd LaHfTaWReOsIrPtAuHg IIIBIVBVBVIBVIIBIBIIB VIIIB d-Block Transition Elements Most have partially occupied d sub-shells in common oxidation states 4 Paper 2, Unit 1, Chapter 1

5 Why are they called d-block elements? Their last electron enters the d-orbital. 5 Paper 2, Unit 1, Chapter 1

6 Most d-block elements are also called transition metals. This is because they exhibit characteristics that ranges from s -block to p – block. Zinc group and Scandium group are NOT considered as transition metals, are called Non-typical Transition elements. 6 Paper 2, Unit 1, Chapter 1

7 What is a transition metal? a transition metal is defined as being an element which forms at least one ion with a partially filled d orbital(s).For this reason, a transition metal is defined as being an element which forms at least one ion with a partially filled d orbital(s). 7 Paper 2, Unit 1, Chapter 1

8 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 – Differences 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 8 Paper 2, Unit 1, Chapter 1

9 Electronic Arrangement ElementZ3d4s Sc21[Ar] Ti22[Ar] V23[Ar] Cr24[Ar] Mn25[Ar] Fe26[Ar] Co27[Ar] Ni28[Ar] Cu29[Ar] Zn30[Ar] 9 Paper 2, Unit 1, Chapter 1

10 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 1 st series of transition elements is that of Ar 1s 2 2s 2 2p 6 3s 2 3p 6 10 Paper 2, Unit 1, Chapter 1

11 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 11 Paper 2, Unit 1, Chapter 1

12 12 Paper 2, Unit 1, Chapter 1 Trends in properties 1.Atomic and Ionic radii Decreases across the series as the atomic no. Increases, due increase in nuclear charge. a)From Sc to Cr - regular expected decrease Increased nuclear attraction b) From Cr to Ni - almost same size nuclear attraction = inter electronic repulsion c) Ni to Zn – Marginal increase nuclear attraction < inter electronic repulsion

13 Paper 2, Unit 1, Chapter Ionization Potential

14 3. Variable Oxidation States D-block elements exhibit variable oxidation states. This means that they can form two or more different types of cations. Examples: Iron can form both Fe² and Fe ³ Manganese can Mn ², Mn³, Mn, Mn and Mn 14 Paper 2, Unit 1, Chapter 1

15 Oxidation States of TMs ScTiVCrMnFeCoNiCuZn Paper 2, Unit 1, Chapter 1

16 Oxidation States of TMs 1. No of OSs 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 OSs 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 16 Paper 2, Unit 1, Chapter 1

17 Stability of OSs General trends 1.Higher OSs become less stable relative to lower ones on moving from left to right across the series 2.Compounds containing TMs in high OSs tend to be oxidising agents e.g MnO Compounds with TMs in low OSs are often reducing agents e.g V 2+ & Fe Paper 2, Unit 1, Chapter 1

18 Oxidation States of TMs In the following table –Most important OSs 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 18 Paper 2, Unit 1, Chapter 1

19 Oxidation States of TMs Nature of bonds – Ionic and covalent –Lower OSs found in ionic compounds E.g. compounds containing Cr 3+, Mn 2+, Fe 3+, Cu 2+ ions –TMs in higher OSs 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 OSs such as V 5+ & Mn 7+ are not formed 19 Paper 2, Unit 1, Chapter 1

20 Oxidising and reducing nature Oxidising and reducing nature – lower oxidation states are highly reducing E.g. V 2+ (aq) & Cr 2+ (aq) strong reducing agents – higher oxidation states are oxidising in nature E.g. Co 3+ is a strong oxidising agent, KMnO 4 - OS +7, K 2 Cr 2 O 7 - OS +6 are oxidising agents 20 Paper 2, Unit 1, Chapter 1 Acidic and basic nature Higher oxidation states are acidic in nature Lower oxidation states become increasingly basic via amphoteric nature H 2 CrO 4 is strong acid – Cr OS +6 Mn 2 O 3 – basic (+3), MnO 2 – amphoteric(+4), KMnO 4 – acidic(+7)

21 Paper 2, Unit 1, Chapter 121 The compounds of the d-block metal ions are usually colored, except, those of d 0 and d 10 metal ions. The colors are due to: Electronic transitions of d-electrons within the d sub-shell. These are known as dd transitions. When light passes through these compounds, electrons from a lower energy d-orbital absorb a photon of energy and are promoted to higher energy d-orbitals. The energy absorbed is equivalent to the energy difference between the two sets of orbitals. Electron while returning from the excited state gives away the energy which falls in visible range of spectrum and the substance appears coloured. Since light of a certain frequency is absorbed, the light that comes out looks coloured because it lacks some colour. The colour of the compound is the complementary of the one that was absorbed Formation of coloured ions

22 Paper 2, Unit 1, Chapter 122 Ferromagnetism and Paramagnetism EOS

23 23 Paper 2, Unit 1, Chapter 1 Magnetic behaviour Electron is a micromagnet, moves 1.On its axis – Spin moment 2.In the orbitals – Orbital moment Total magnetic moment = Spin moment + Orbital moment µ (S + L) = 4S (S+1) + L( L + 1) Orbital moment is negligible, µ eff. = n(n+2) B.M.

24 Paper 2, Unit 1, Chapter 124 [Ar] 4s 2 3d 2 [Kr] 5s 2 4d 2 [Xe] 6s 2 4f 14 5d 2 [Rn] 7s 2 5f 14 6d 2 Quite unreactive Fairly inactive element Not very reactive Highly radioactive Titanium Zirconium Hafnium Rutherfordium

25 Paper 2, Unit 1, Chapter 125

26 Paper 2, Unit 1, Chapter 126 [Ar] 4s 1 3d 5 [Kr] 5s 1 4d 5 [Xe] 6s 1 4f 14 5d 5

27 Paper 2, Unit 1, Chapter 127

28 Paper 2, Unit 1, Chapter 128

29 Paper 2, Unit 1, Chapter 129

30 Paper 2, Unit 1, Chapter 130

31 Paper 2, Unit 1, Chapter 131


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