XII d & f block elements Notes.pptx

Chemistry d&f block elememts

1. DAV CALDERYS PUBLIC SCHOOL KATNI, Madhya Pradesh d & f block Element

2. TOPICS THE POSITION IN PERIODIC TABLE. THE TRANSITION ELEMENT. ELECTRONIC CONFIGURATION . PHYSICAL PROPERTIES OF THE TRANSITION ELEMENTS . VARIATION IN ATOMIC AND IONIC SIZES. IONISATION ENTHALPIES . OXIDATION STATES. TRENDS IN THE M 2+ /M SEP. TRENDS IN THE M3+/M2+ SEP. TRENDS IN THE STABILITY OF HIGHER OXIDATION

3. POSITION IN THE PERIODIC TABLE

4. ELECTRONIC CONFIGURATION [n-1]d 1-10 ns 1-2 AT. NO. 21 22 23 24 25 26 27 28 29 30 ELE. Sc Ti V Cr Mn Fe Co Ni Cu Zn E.C 3d1 4s2 3d2 4s2 3d3 4s2 3d5 4s1 3d5 4s2 3d6 4 s2 3d7 4 s2 3d8 4 s2 3d10 4s1 3d10 4s2 First [3d] Transition element series[sc- zn ]

5. At. No. Element E.C 39 Y 4d1 5s2 40 Zr 4d2 5s2 41 Nb 4d4 5s1 42 Mo 4d5 5s1 43 Tc 4d6 5s1 44 Ru 4d7 5s1 45 Rh 4d8 5s1 46 Pd 4d10 5s0 47 Ag 4d10 5s1 48 Cd 4d10 5s2 At .No. ELEMENT 57 La 72 Hf 73 Ta 74 W 75 Re 76 Os 77 Ir 78 Pt 79 Au 80 Hg E.C 5d1 6s2 5d2 6s2 5d3 6s2 5d4 6s2 5d5 6s2 5d6 6s2 5d7 6s2 5d9 6s1 5d10 6s1 5d10 6s2 Second [4d] transition series Third [5d] transition series

6. Exceptional configuration of Cr and Cu

7. THE TRANSITION ELEMENTS

8. Physical Properties of Transition elements They show variable oxidation state. They have high melting and boiling point They have a great tendency to form complexes. They form alloys. They are electropositive in nature. Most of the transition elements form coloured compounds. Their compounds are generally paramagnetic in nature. They form interstitial compounds.

9. Trends in the properties of transition elements Atomic and Ionic radii The atomic radii of d-block elements in a series decrease with increase in atomic number as the nuclear charge increases whereas the shielding effect of d-e - is small. At the end of the period, there is slight increase in the atomic radii . Sc Ti V Cr Mn Fe Co Ni Cu Zn 162 147 134 127 126 126 125 124 124 138

10. IONISATION ENTHALPIES The ionisation enthalpy gradually increase with increase in atomic number along a given transition series. EX –The increasing ionisation enthalpies are due to increased nuclear charge with increase in atomic number which reduces the size of the atom making the removal of outer e - difficult.

11. Metallic character Except mercury which is a liquid ,all the transition element have typical metallic structure[ hcp , ccp or bcc] They exhibits all the characteristics of metals. For ex- They are hard, lustrous, malleable and ductile etc . Melting and Boiling point The transition metals have very high melting and boiling point .The melting points of the transition metals rise to a maximum and then fall as the atomic number increases .

12. Oxidation state scandium is one of the two elements in the first transition metal period which has only one oxidation state [zinc is the other ,with an oxidation state of 2]. All the other elements have at least two different oxidation states. Manganese ,which is in the middle of the period, has the highest number of oxidation states. Copper and chromium do not follow the general formula for transition metal oxidation state. B’coz Cu has 9 d-e-, which would produce 4 paired d-electrons and 1 unpaired d-e-.since Cu is just 1 e- short of having a completely full d-orbital ,it steals an e- from the s-orbital, allowing it to have 10 d-e-.Likewise, Cr has 4 d-e-,only one short of having a half filled d-orbital, so it steals electron from the s-orbital, allowing Cr to have 5 d-electrons.

13. Oxidation states of 1 st series . Sc Ti V Cr Mn Fe Co Ni Cu Zn +1 +2 +2 +2 +2 +2 +2 +2 +2 +2 +3 +3 +3 +3 +3 +3 +3 +3 +4 +4 +4 +4 +4 +4 +4 +5 +5 +5 +6 +6 +6 +7

14. Trends in the M3+/M standard electrode potentials. A very low value for Electrode [sc3+/Sc2+] reflects the stability of Sc3+ ion which a noble gas configuration For Sc Sc [21]= [ Ar ]3d1 4s2 Sc[21]2+ = [ Ar ] 3d1 4s0 Sc [21]3+= [ Ar ] 3d0 4s0 The highest value for Zn is on account of very high stability of Zn2+ ion with d10 configuration.

15. Trends in the M2+/M Standard Electrode Potential. There is no regular trend in electrode [M2+/M] values. This is because their ionization enthalpies and sublimation enthalpies do not show any regular trend. The general trend towards less negative electrode values along the series is due to the general increase in the sum of first and second ionization enthalpies. Cu shows a unique behaviour in the series as it is the only metal having positive value for electrode. Reason = As its sublimation and I.E does compensate with hydration enthalpy.

16. Chemical Reactivity and Electrode values Electrode values of a metal ion in solution is determine by 3 type of enthalpies i.e., Sublimation ,Ionization , hydration enthalpy . H[S] H+[ aq ] H[g] H+[g] USING HESS LAW = H =sub + I.E+ Hyd enthalpy

17. The metals of the first transition series [except Cu] are relatively more reactive than the others series. Less negative electrode values for M2+/M along the series indicate a decreasing tendency to form divalent cations . More negative electrode values than expected for Mn , Ni, and Zn show greater stability for Zn2+,Ni2+and Zn2+.