T - F Knowing that a Lewis dot structure can be written for the compound XY2, where Y ... 1) resonance; 2) sp hybrids; 3) sp2 hybrids; 4) sp3d hybrids. 12.
Chemistry I-Honors Chemical Bonding Review Sheet Answer Key
1. T - F Chemical bonds never form unless half-filled orbitals are originally available in the central atom.
2. T - F A reasonable formula for a compound of aluminum and bromine would be Al3Br7.
3. T - F The strength of the attractive force between two bonded atoms increases, and the length of the bond increases, in the order: single bond < double bond < triple bond.
4. T - F Knowing that a Lewis dot structure can be written for the compound XY2, where Y corresponds to an element in Group 7-A of the periodic table, and that the octet rule is obeyed, you can be reasonably sure that the neutral atom of element X has two pairs of unpaired "valence" electrons. (It has two lone pairs as well as two bonding pairs).
5. The ion, Ni2+ would have the electron configuration: 1) [Ar] 3d8 4s2; 2) [Ar] 3d8; 3) [Ar] 3d7 4s; 4) [Ar] 3d6 4s2 5) none of these.
6. Of the elements listed, which would you expect to have the greatest attraction toward a pair of nonbonding electrons? (Which would most like to be the acceptor of an electron pair in a coordinate covalent bond?) 1) Al3+; 2) Li1+; 3) Fe2+; 4) S-2; 5) Ba2+
7. Which one of the following contains both ionic and covalent bonds?
1) NaOH; 2) HOH; 3) CH4; 4) SiO2; 5) HCN.
8. Which one of the following bonds would be the least polar? 1) H-F; 2) O-F; 3) Cl-F; 4) Ca-F; 5) S- Br
9. The fact that all bonds in sulfur trioxide are the same even though no single drawing can represent the structure is accounted for by: 1) the concept of resonance; 2) the Lewis octet rule; 3) electron repulsion theory; 4) sulfur always forms three bonds.
10. Indicate which of the following is definitely a polar molecule: 1) O2; 2) CO2; 3) BF3; 4) methane (CH4); 5) HCl gas.
11. The fact that the BeF2 molecule is linear implies that the Be-F bonds involve: 1) resonance; 2) sp hybrids; 3) sp2 hybrids; 4) sp3d hybrids.
12. Which of the following species would be predicted to be paramagnetic? 1) oxygen gas molecule; 2) neutral Fe atom; 3) neutral Zn atom; 4) Zn (+2) ion; 5) both 1 and 2.
13. Which of the following contains a triple covalent bond? 1) HCN; 2) O2; 3) HCl; 4) ammonia (NH3); 5) hydrogen gas.
14. The bonding that is involved in the formation of brass - an alloy of copper and zinc - is most probably: 1) ionic; 2) metallic; 3) pure covalent; 4) coordinate covalent; 5) van der Waals.
15. If a molecule contains one pi bond between two atoms, what type of bond is exhibited? 1) single bond; 2) double bond; 3) triple bond; 4) co-ordinate covalent bond.
16. Which of the following ions shows resonance? 1) carbonate; 2) chlorate; 3) phosphate; 4) nitrate; 5) both 1 and 4 exhibit resonance.
17. Which is a characteristic of covalent network solids? 1) they are good electrical insulators; 2) they have low melting points; 3) they have high vapor pressure (they tend to boil easily); 4) they are very malleable.
18. Hydrogen bonds would be strongest between the molecules of a compound containing hydrogen and a compound containing: 1) iodine; 2) fluorine; 3) carbon; 4) chlorine; 5) nitrogen.
19. Which is a characteristic of ionic solids? 1) they conduct electricity; 2) they have high vapor pressure; 3) they have high melting points; 4) they are very malleable.
20. The transfer of electrons from potassium atoms to bromine atoms results in the formation of: 1) coordinate covalent bonds; 2) polar covalent bonds; 3) metallic bonds; 4) nonpolar covalent bonds; 5) ionic bonds.
21. Which of the following compounds would be expected to show a violation of the octet rule with respect to the central atom? 1) AsCl3; 2) NO2; 3) N2O; 4) BF3; 5) both 2 and 4.
22. Which molecule has polar bonds, but is a nonpolar molecule? 1) ammonia; 2) boron trifluoride; 3) hydrogen cyanide; 4) water; 5) sodium chloride.
23. Which of the following molecules shows coordinate covalent (dative) bonding? 1) NH3; 2) CO; 3) CO2; 4) H2O; 5) NH4+1.
24. In the compound - hydrogen peroxide (H2O2), the two oxygen atoms are bonded to each other and one hydrogen is then attached to each oxygen. What type of bond holds the two oxygen atoms together? 1) single covalent bond; 2) double covalent bond; 3) triple covalent bond; 4) an ionic bond; 5) a coordinate covalent bond.
25. The energy required to remove an electron from the outer shell is called: 1) bond energy; 2) ionization energy; 3) hybridization energy; 4) activation energy; 5) electron affinity.
26. The bonds within most polyatomic ions are predominantly: 1) coordinate covalent; 2) ionic; 3) metallic; 4) van der Waals; 5) covalent.
27. Which of the following compounds shows the least amount of ionic character in its bonds? 1) MgCl2; 2) BF3; 3) NH3; 4) CsI; 5) Li2O. 1.85 1.94 0.94 1.87 2.46
28. The smallest chemical unit of a substance (other than the noble gases) capable of stable, independent existence would be which of the following? 1) cation; 2) anion; 3) molecule; 4) resonant ion.
29. Which of the following compounds has nonpolar bonds and is a nonpolar molecule? 1) SO2; 2) TeBr2; 3) CS2; 4) CO2; 5) both 3 and 4.
30. If an element gains two electrons in a chemical reaction, this element is said to be: 1) oxidized; 2) reduced; 3) polarized.
If a statement is false, indicate what is incorrect about the statement:
31. T - F If the central atom in a molecule exhibits true sp3d2 hybridization, then this atom must have at least a [Ne] core configuration.
32. T - F The water molecule contains polar bonds and is a polar molecule.
33. T - F The greatest amount of ionic character would be expected to come from a very large metallic atom with a charge of +1 bonded to a very small nonmetallic atom with a -1 charge.
For the following compounds, tell what type of intramolecular bond exists. Use the following key: (1) ionic; (2) pure covalent; (3) polar covalent; (4) nonpolar covalent; (5) metallic
34. liquid bromine (2)
35. solid iodine (2)
36. calcium sulfide (1)
37. solid sodium (5)
38. liquid mercury (5)
39. phosphorus pentachloride (3)
40. selenium dibromide (4)
41. fluorine gas (2)
42. carbon dioxide (3)
43. magnesium bromide (1)
44. How many pi bonds exist in ethyne, HCCH? (The atoms are arranged in this order.) 1) 1; 2) 2; 3) 3; 4) 4; 5) 0
For the following compounds, tell what type of intermolecular bond exists. Use the following key: (1) ionic; (2) covalent (network); (3) hydrogen; (4) dipole- dipole (molecular); (5) metallic (6) van der Waals (London dispersion forces); (7) ion - induced dipole
45. liquid bromine (6)
46. solid iodine added to (7) sodium chloride vapor
47. hydrogen sulfide gas (6)
48. solid sodium (5)
49. hydrofluoric acid (3)
50. phosphorus pentachloride (6)
51. water (3)
52. fluorine gas (6)
53. carbon monoxide (4)
54. magnesium bromide (1)
55. diamond (2)
56. potassium chloride (1)
= = = = = = = = = = = = = = = = = = = = =
57. How many different isomers can exist for C5H12 (not counting cyclic forms)?
n-pentane, 2-methylbutane or isopentane, 2,2-dimethylpropane or neopentane
58. Draw the cis- and the trans- isomers of dichloroethene.
Cl Cl Cl H \ / \ / C==C ( cis C==C ( trans / \ / \ H H H Cl
59. Why are the geometric isomers (cis and trans) not available for 1,1- dichloroethene?
Both of the chloride ions are on the same carbon, so there is no way for them to be “on the same side” or “across” the double bond.
Draw of the Lewis structures for the following species: (Be sure to include all resonant forms)
__ -2 60. sulfate ion |O|
S |O| |O|
61. nitrite ion
N N ( ( O O O O
62. phosphorus trichloride ___ P |Cl| |Cl|
63. carbon monoxide |C O|
| F | 64. boron trifluoride | B / \ | F | | F | __ __ 65. beryllium chloride | Cl -- Be -- Cl |
66. nitrogen dioxide . . N N // \ / \\ |O| |O| |O| |O|
67. selenium hexafluoride |F| |F | F| Se |F | F| |F|
68. sulfite ion -2 S
|O| |O| |O|
69. Explain why the benzene molecule is planar while cyclohexane has both a "chair" and a "boat" form - both of which are nonlinear. What is the bond angle in the benzene molecule? What is the bond angle in the cyclohexane molecule? The carbons in benzene exhibit sp2 hybridization which makes all of the atoms lie in a trigonal planar arrangement, while atoms around the carbons in cyclohexane are influenced by the sp3 hybridization. Bond angle in benzene is 120o while it is 109.5o for cyclohexane.
70. Both AsF3 and AsF5 exist while only the NF3 molecule exists and NF5 doesn't. Why is that?
The arsenic atom can extend electrons into the 3d subshell, exhibiting the sp3d hybridization while nitrogen, with electrons only in the second shell cannot move electrons into a “d” subshell without exerting way too much energy.