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1. A chemical bond is primarily a:
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2. Noble gases (He, Ne, Ar, etc.) are generally unreactive due to their:
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3. The 'octet rule' refers to the tendency of atoms to attain ___ electrons in their valence shell.
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4. Atoms form chemical bonds primarily because it leads to:
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5. When two hydrogen atoms approach each other to form H₂, the potential energy of the system:
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6. The distance between two bonded hydrogen atoms where potential energy is minimum (75.4 pm) is called the:
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7. The energy released when a bond is formed (e.g., 436.45 kJ/mol for H₂) is called:
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8. Atomic radius generally refers to the average distance between the nucleus and the:
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9. Why can't the atomic radius be determined precisely?
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10. Atomic radii generally ___ from left to right across a period.
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11. The decrease in atomic radii across a period is mainly due to:
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12. Atomic radii generally ___ from top to bottom within a group.
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13. The increase in atomic radii down a group is mainly due to:
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14. The ionic radius of a cation (e.g., Na⁺) is ___ than the atomic radius of the parent atom (Na).
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15. The ionic radius of an anion (e.g., Cl⁻) is ___ than the atomic radius of the parent atom (Cl).
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16. Why is a cation smaller than its parent atom?
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17. Why is an anion larger than its parent atom?
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18. The interionic distance (R) in a crystal like KCl is approximately:
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19. Covalent radius is defined as ___ the single bond length between two similar atoms.
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20. If the C-C bond length is 154 pm and Cl-Cl is 198 pm, the expected C-Cl bond length (additive) is:
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21. Ionization energy is the minimum energy required to:
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22. Which factor does NOT directly influence ionization energy?
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23. Ionization energy generally ___ from left to right across a period.
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24. Ionization energy generally ___ from top to bottom within a group.
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25. The second ionization energy of an atom is always ___ than its first ionization energy.
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26. Elements with low ionization energies are typically:
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27. Electron affinity is the energy ___ when an electron is added to a gaseous atom.
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28. Electron affinity is a measure of the attraction of the nucleus for:
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29. Electron affinity generally ___ from left to right across a period (excluding exceptions).
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30. Electron affinity generally ___ from top to bottom within a group (excluding exceptions).
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31. Why does Fluorine have a lower electron affinity than Chlorine?
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32. Electronegativity is the tendency of an atom to:
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33. Which element has the highest electronegativity value (set to 4.0 on Pauling scale)?
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34. Electronegativity generally ___ from left to right across a period.
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35. Electronegativity generally ___ from top to bottom within a group.
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36. A large difference in electronegativity between two bonded atoms leads to a(n) ___ bond.
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37. An ionic bond typically forms between an atom with low ___ and an atom with high ___.
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38. Ionic compounds form crystal lattices held together by:
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39. The energy released during the formation of one mole of an ionic crystal lattice from gaseous ions is called:
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40. Which compound is expected to have the most ionic character?
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41. A covalent bond is formed by:
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42. In a non-polar covalent bond, the electron pair is shared:
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43. Which molecule contains only non-polar covalent bonds?
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44. Why is CCl₄ considered a non-polar molecule despite having polar C-Cl bonds?
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45. In a polar covalent bond (e.g., H-F), the shared electron pair is displaced towards the atom with:
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46. A bond where the shared electron pair is donated entirely by one of the bonded atoms is called a:
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47. In the formation of the adduct NH₃ → BF₃, the donor atom is ___ and the acceptor atom is ___.
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48. The formation of the hydronium ion (H₃O⁺) from H₂O and H⁺ involves a:
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49. After formation, is the coordinate covalent bond in NH₄⁺ distinguishable from the other N-H covalent bonds?
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50. The VSEPR theory predicts molecular shapes based on the repulsion between:
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51. According to VSEPR, electron pairs arrange themselves around a central atom to:
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52. Which type of electron pair exerts the greatest repulsive force according to VSEPR?
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53. In VSEPR theory, double and triple bonds are treated as ___ in determining overall geometry.
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54. A molecule of type AB₂ with no lone pairs on A (like BeCl₂) will have which geometry?
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55. The bond angle in a linear AB₂ molecule is:
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56. A molecule of type AB₃ with no lone pairs on A (like BF₃) will have which geometry?
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57. The bond angles in a trigonal planar AB₃ molecule are:
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58. A molecule of type AB₃ with one lone pair on A (like NH₃) will have which molecular geometry?
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59. The bond angle in NH₃ is approximately:
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60. A molecule of type AB₄ with no lone pairs on A (like CH₄) will have which geometry?
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61. The bond angles in a tetrahedral AB₄ molecule are:
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62. A molecule of type AB₂ with two lone pairs on A (like H₂O) will have which molecular geometry?
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63. The bond angle in H₂O is approximately:
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64. Why is the bond angle in H₂O smaller than in NH₃?
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65. Valence Bond Theory (VBT) describes covalent bond formation as the ___ of half-filled atomic orbitals.
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66. A bond formed by the direct, head-on overlap of orbitals along the internuclear axis is called a:
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67. A bond formed by the sideways overlap of parallel p orbitals above and below the internuclear axis is called a:
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68. The concept introduced to explain equivalent bonds and observed geometries (like in CH₄) is:
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69. sp³ hybridization involves the mixing of:
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70. How many sp³ hybrid orbitals are formed from one s and three p orbitals?
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71. The geometry associated with sp³ hybridization is:
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72. The hybridization of the central carbon atom in methane (CH₄) is:
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73. The hybridization of the central nitrogen atom in ammonia (NH₃) is:
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74. The hybridization of the central oxygen atom in water (H₂O) is:
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75. sp² hybridization involves the mixing of:
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76. The geometry associated with sp² hybridization is:
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77. The hybridization of the boron atom in BF₃ is:
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78. The hybridization of the carbon atoms in ethene (C₂H₄) is:
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79. The double bond in ethene (C₂H₄) consists of:
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80. sp hybridization involves the mixing of:
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81. The geometry associated with sp hybridization is:
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82. The hybridization of the beryllium atom in BeCl₂ is:
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83. The hybridization of the carbon atoms in ethyne (C₂H₂) is:
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84. The triple bond in ethyne (C₂H₂) consists of: