F block element

based on maharashtra board 2015 syllabus.

1. F – BLOCK ELEMENT (n-2)f

2. Introduction Penultimate (n -1)d prepenultimate (n -2)f Inner transition element- e - use is both shell. Intermediate behavior like d- block element. 2 series of f- block element- Lanthanide series – our main topic. actinide series- radioactive.

3. Lanthanide series La(57) Ce (58) Pr (59) Nd (60) Pm(61) Sm (62) Eu (63) Gd (64) Tb(65) Dy (66) Ho(67) Er (68) Tm(69) Yb (70) Lu(71) 14 element is called lanthanide series. General electronic configuration 4f 1-14 5d 0-1 6s 2

4. Ln Greek hidden Lanthanum, a “rare earth” is used in camera lenses amongst other things. Lanthanum is found in uranium minerals

5. Cerium Sparking light. Also used in permanent magnet.

6. Praseodymium

7. Praseodymium

8. Neodymium

9. Neodymium- strong magnet

10. Neodymium

11. Europeium

12. Europium is used to produce blue, red and white radiances in computer monitors and television screens. It is also used in energy efficient light bulbs.

13. Position of lanthanoids 13 6 7 57 -71 89-103 Total= 14 element Same no. of valency 5d 1 and 6s 2 . Same chemical & physical property. Fill orbital 4f 5f

14. Electronic configuration of lanthanoids E.C Based on aufbau principle . La (57) 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 5s 2 5p 6 5d 1 6s 2 [ Xe ] – 54 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 5s 2 5p 6 The electronic configuration of Ln is [ Xe ] 4f 5d 1 6s 2 or [ Xe ] 4f Similarly Ce - 4f 1 , Pr - 4f 2 ,……… Lu-4f 14 .( expected ) but observed E.C is not true for all element.

15. Electronic configuration of lanthanoids

16. Oxidation state Common oxidation state is +3 more stable. Loses of two 6s electron and one 5d or 4f electron. Some either show +2 or +4 Oxidation state. Ln [ Xe ] 4f 5d 1 6s 2 and Ln+3 [ Xe ]4f 5d 6s Ln, Pm, Ho, Eb , Lu +3 Ce , Pr , Tb, Dy +3, +4 Sm , Eu , Tm, Yb +2, +3 Nd , +2, +3, +3

17. Chemical reactivity of Lanthanids Carbides-C Hydrides- H 2 Oxides- O 2 Reaction with nitrogen Reaction with mineral acids Reaction with water Reaction with sulphure

18. The first few members of the lanthanoids are quite reactive and show chemical behaviour similar to that of calcium. The standard electrode potentials of the Ln +3 /Ln couple indicate that all the lanthanides are more reactive than aluminium. These metals combine with hydrogen when heated gently in the gas, and form hydrides of the type LnH 2  and LnH 3 . Chemical reactivity of Lanthanids

19. lanthanoids (Ln) Ln             +             3H 2            →               2LnH 3 lanthanoid              Hydrogen                  Lanthanoid hydride 2Ln              +             3O 2            →               2Ln 2 O 3 lanthanoid              Oxygen                  Lanthanoid Oxide The oxide Ln 2 O 3 react with water to form insoluble hydroxides. Ln 2 O 3 + 3H 2 O → 2Ln(OH) 3 Ln 2 O 3 + 3CO 2 → Ln 2 (CO 3 ) 3 Chemical reactivity of Lanthanids

20. On being heated, these elements combine directly with non-metals, and form carbides with carbon, nitrides with nitrogen, sulphides with sulphur, and halides with halogens.                                   2773K Ln        +             2C      →          2LnC 2 lanthanoid             carbon                 Carbide                                              Δ 2 Ln        +             N 2             →          2LnN lanthanoid             Nitrogen                 Nitride                                              Δ 2 Ln        +             3S             →          2Ln 2 S 3 lanthanoid             Sulphur                    Sulphide   Chemical reactivity of Lanthanids

21.   2 Ln        +             3H 2 O          →          2Ln(OH) 3 + 3H 2 lanthanoid              water                 Halide They liberate hydrogen from dilute acids.                                              Δ      2 Ln        +           6HX        →          2LnX 3     +    3H 2 ↑ lanthanoid               Nitrogen          Halide        hydrogen Chemical reactivity of Lanthanids

22. Lanthanoid contraction and its consequences

23. Lanthanoid contraction The gradual decrease in atomic and ionic size of lanthanoides with increase in atomic number is called lanthanoide contraction. Causes of Lanthanoid contraction- As atomic no. increase the positive charge also increase. As atomic no. increase other thing decreases Atomic radius= ionic radius > screen effect.

24. Effects of Lanthanoid contraction Decrease in basicity-( fajan’s principle) Larger the size of cation , greater is the tendency of such hydroxides to dissociate(weak bond) and stronger will be the base(Covalent nature).

25. b) Ionic radii of post lanthanoids The element which follow the lanthanoids in the third transition series are known as post lanthanoids . The ionic radii of the element which follow lanthanium ( Hf , Ta, W, etc ) are similar to that of the element of previous period. There is normal increase in size Sc to Y to La. Effects of Lanthanoid contraction

26. Group  Series ↓ 4 5 6 7 1 st transition Ti(132pm) V(122pm) Cr(106pm) Mn (94pm) 2 nd transition Zr (145pm) Nb (134pm) Mo(129pm) Tc (114pm) 3 rd transition Hf (144pm) Ta(134pm) W(130pm) Re(114pm) Effects of Lanthanoid contraction This are similar no. of valency and property is called chemical twins .

27. Actinoids 7 period and actinide series. Electron enter in 5f orbital. Many physical and chemical property are similar to actinium( actinoids ). Second inner transition element. Outermost and penultimate shell remain the same. General E.C 5f 1-10 6d 0-1 7s 2

28. Actinide Np (93)- Neptune Pu (94)

29. Trans-uranic element Manmade element atomic no. higher then uranium-92.

30. Electronic configuration Ac (89)- 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 5s 2 5p 6 4f 14 5d 10 6s 2 6p 6 6d 1 7s 2 . [ Rn ]- 86 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 5s 2 5p 6 4f 14 5d 10 6s 2 6p 6 Ac electronic configuration is [ Rn ] 6d 1 7s 2 or [ Rn ] 5f 6d 1 7s 2 6d and 7s electron is same only 5f electron change by increasing order. Th (90)- [ Rn ] 5f 1 ,…….. 5f 10 .

31. Electronic configuration

32. Oxidation state of actinoids Common oxidation state is +3. Np+3, Pu+3 get oxidised Np+4,Pu+4 in aqs soln. some become stable some unstable. Ac Th Pa U Np Am Cm Bk Cf Es Fm Md No Lr 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 4 4 4 4 4 4 5 5 5 5 5 6 6 6 6 7 7

33. Comparison between lanthanoids and actinoids