10. Chemical bonding

2 & 3 Marks

1. What are Chemical bonds?

2. State Octet rule.

3. Explain the Octet rule.

4. What is a Covalent bond?

5. What is a Single covalent bond? Give suitable examples.

6. What is a Double covalent bond? Give suitable examples.

7. What is a Triple covalent bond? Give suitable examples.

8. What is Lewis structure? Or What is Lewis dot structure?

9. Sketch the Lewis structures of i) Ammonia (NH3)  ii) Methane iii) Dinitrogen Pentoxide (N2O5).

10. Draw the Lewis structures for the following species. 

      i) NO3–        ii) SO42 –                iii) HNO3               iv) O3

11. Draw the Lewis structures for i) Nitrous acid (HNO2)  ii) Phosphoric acid 

      iii) Sulphur trioxide (SO3).

12. What is Formal charge of an atom?

13. Calculate the Formal charge on all atoms in .

14. Calculate the Formal charge on all atoms in .

15. Calculate the Formal charge on each atom of i) Carbonyl chloride (COCl2)

      ii) NO2          iii) Nitric oxide.

16. Give the Guidelines for the selection of the best representation of Lewis structure.

17. How are Lewis structures for Exceptions to the Octet rule categorized?

18. Give Examples for Molecules with Electron deficient central atoms and Draw their Lewis structures.

19. Give Examples for Molecules containing Odd electrons and Draw their Lewis structures.

20. Give Examples for Molecules with Expanded valence shells and Draw their Lewis structures.

21. What is Ionic bond? Or What is Electrovalent bond?

22. What is Coordinate covalent bond? Or What is Coordinate bond?

23. Name the Bond parameters a Covalent bond is characterised by.

24. What is Bond length?

25. How can you Calculate the Bond length from the radii of the bonded atoms in a covalent molecule?

26. What are the Techniques used to determine the length of a bond?

27. On what Factors does the Bond length depend on?

28. How is the Size of the atom related to Bond length? Give example.

29. How is the Number of bonds (Multiplicity) between the atoms related to Bond length? Give example.

30. Define Bond order.

31. What is Bond order according to Lewis theory?

32. What is Bond angle? How is it expressed?

33. Define Bond enthalpy. What is its Unit? Or Define Bond energy. What is its Unit?

34. On what Factors does the Bond enthalpy value depend on?

35. How is the Size of the atom related to Bond enthalpy?

36. Where is the term Average bond enthalpy used? Explain with an example.

37. Problem In water the energy needed to break two OH bonds is given below.

      H2O(g) ---> H(g) + OH(g)         ΔH1 = 502 kJ mol–1

      OH(g) ---> H(g) + O(g)              ΔH2 = 427 kJ mol–1

      Calculate the Average bond enthalpy of OH bond in water.

38. What are Resonance structures? Or What are Canonical structures?

40. What is a Resonance hybrid?

41. What is Resonance energy?

42. Write / Sketch the Resonance structures for i) Ozone molecule   ii) N2O.

43. What is Polar Covalent bond? Explain with example.

44.The H - F bond is said to be Polar covalent bond - Explain.

45. A covalent bond formed between two identical atoms is Non polar - Explain. Or

      H2, N2, O2, F2, Cl2, Br2 and I2 are Non polar molecules - Explain. Or

      Homo diatomic molecules are Non polar molecules - Explain.

46. What is Dipolment? Give its Units. Or Define Dipolment. Give its Units.

47. Linear form of Carbon dioxide molecule has two polar bonds. Yet the molecule has Zero Dipole moment. Why?

48. Both CO2 and H2O are triatomic molecule but their Dipole moment values are different. Why?

49. Apply the concept of Electronegativity to explain the Polarity of Covalent bonds.

50. Of the two molecules OCS and CS2 which one has Higher Dipole moment value? Why?

51. What is Polarisation?

52. What is Polarising ability?

53. What is Polarisability?

54. Arrange AlCl3, NaCl and MgCl2 in the Increasing order of Covalent character.

55. Lithium chloride is more Covalent than Sodium chloride - Explain.

56. Lithium iodide is more Covalent than Lithium chloride - Explain.

57. CuCl is more Covalent than NaCl - Explain.

58. Arrange the following in the decreasing order of Bond angle

      i) CH4, H2O, NH3              ii) C2H2, BF3, CCl4.

59. Define σ - bond.  Or What is a Sigma bond?

60. Considering x - axis as Molecular axis, which out of the following will form a Sigma bond?

      i) 1s and 2py         ii) 2Px and 2Px           iii) 2px and 2pz           iv) 1s and 2pz

61. What is a pi bond? Or Define π - bond.

62. Which bond is stronger σ or π? Why?

63. Differentiate: σ - bond and π - bond.

64. Discuss the Formation of Hydrogen molecule on the basis of Overlap.

65. Formation of Fluorine molecule on the basis of Overlap.

66. Formation of HF molecule on the basis of Overlap.

67. Formation of Oxygen molecule on the basis of Overlap.

68. Define Hybridisation.

69. What type of Hybridisations are possible in the following Geometries?

       a) Octahedral                          b) Tetrahedral                          c) Square planer

70. How can you calculate the bond order of a molecule?

71. What are the principles governed by in the filling of molecular orbitals?

5 Marks

1. Describe Kossel - Lewis approach to Chemical bonding.

2. Give the various Steps for writing the Lewis structure for a given compound.

3. Explain the Ionic bond formation in Potassium chloride (KCl).

4. Explain the Ionic bond formation in MgO.

5. Explain the Ionic bond formation in CaF2.

6. Explain the bond formation in MgCl2.

7. Describe Bond length.

8. Describe Bond order.

9. What is Bond order between bonded atoms in H2, O2, N2, H2O, HCl, HCN, HCHO, C2H4 and CH4?

10. Describe Bond enthalpy. Or Describe Bond energy.

11. Explain Resonance with reference to Carbonate ion.

12. Explain the Covalent character in Ionic bond.

13. Describe Fajan's rule.

14. Give the Important principles of VSEPR Theory. Or Explain VSEPR Theory.

15. Apply VSEPR Theory to predict the Shape of SF6.

16. Apply VSEPR Theory to predict the Shape of IF7.

17. Bond angle in PH4+ is higher than in PH3. Why?

18. Explain the Valence bond approach for the formation of covalent bonds. Or

      Discuss a simple qualitative treatment of VB theory for the formation of Hydrogen molecule.

19. Give the Salient features of VB Theory.

20. Explain the Bond formation in BeCl2 and Sketch shape. Or

      Explain sp hybridisation in BeCl2 and Sketch shape.

21. Explain sp2 hybridisation in BF3 and Sketch shape.

22. Explain sp3 hybridisation in CH4 and Sketch shape.

23. Explain the bond formation in CCl4 using Hybridisation concept.

24. In CH4, NH3 and H2O, the central atom undergoes sp3 Hybridisation - yet their bond angles are

      different. Why?

25. Explain sp3d hybridisation in PCl5 and Sketch shape.

26. Explain sp3d2 hybridisation in SF6 and Sketch shape.

27. Explain the bond formation in SF4 using Hybridisation concept.

28. Explain the bond formation in Ethylene.

29. Explain the bond formation in Acetylene.

30. Write the Salient features of Molecular orbital theory.

31. What do you understand by Linear combination of atomic orbitals in MO theory?

32. Discuss the formation of H2 molecule using MO Theory.

33. Hydrogen gas is Diatomic where as Inert gases are Mono atomic - Explain on the basis of MO Theory.

34. Discuss the formation of Li2 molecule using MO Theory.

35. Discuss the formation of B2 molecule using MO Theory.

36. Discuss the formation of C2 molecule using MO Theory.

37. Discuss the formation of N2 molecule using MO Theory.

38. Draw the M.O diagram for O2 molecule, Calculate its Bond order and show that O2 is Paramagnetic.

39. Draw MO diagram of CO and Calculate its Bond order.

40. Explain the MO Theory, Calculate the Bond order and explain the Magnetic properties of NO.

41. Draw the MO diagram for Acetylide ion C22 – and Calculate its Bond order.

42. Which one of the following has Highest Bond order?  N2, N2+ or N2–

43. The observed bond length of N2+ is Larger than N2 while the bond length in NO+ is Less than in NO. Why?

44. Describe Metallic bonding briefly.