Unit 4 Study Guide: Chemical Bonding
1. T - F Chemical bonds never form unless partially-filled orbitals are originally available in the central atom.
2. 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.
3. Which one of the following contains both ionic and covalent bonds?
1) NaOH; 2) HOH;
3) CH4;
4) SiO2;
5) HCN.
4. 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
5. 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.
6.
Indicate which of the following is definitely a polar molecule:
1) O2; 2) CO2;
3) BF3;
4) methane (CH4);
5) HCl gas.
7.
Which of the following contains a triple covalent bond?
1) HCN;2) O2; 3) HCl; 4) ammonia (NH3); 5) hydrogen gas.
8.
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.
9. Which of the following ions shows resonance?
1) carbonate;
2) chlorate;
3) phosphate;
4) nitrate;
5) both 1 and 4 exhibit resonance.
10. 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.
11. 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.
12. Which is a characteristic of ionic solids?
1) they conduct electricity; 2) they have high vapor pressure;
they are very malleable.
3) they have high melting points;4)
13. 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.
14. 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.
15. Which molecule has polar bonds, but is a nonpolar molecule?
1) ammonia;
2) boron trifluoride;3) hydrogen cyanide; 4) water;
5) sodium chloride.
16. 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;
coordinate covalent bond.
17. The bonds within most polyatomic ions are predominantly:
1) coordinate covalent; 2) ionic;
3) metallic; 4) van der Waals;
5) covalent.
18. 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
19. 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.
20. 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.
21. Metals are good conductors of electricity because they: 1) form crystal lattices
3) contain mobile valence electrons 4) form ionic bonds
2) contain positive ions
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
22. liquid bromine Br2
(2/4)
23. solid iodine I2
(2,4)
24. calcium sulfide CaS
(1)
25. solid sodium Na
(5)
26. liquid mercury Hg
(5)
27. phosphoruspentachloride PCl5 (3)
28. seleniumdibromide SeBr2
(4)
29. fluorine gas F2
30. carbon dioxide CO2
(3)
31. magnesium bromide MgBr2
(2/4)
(1)
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
32. liquid bromine
(6)
33. hydrogen sulfide gas
34. solid sodium
(5)
35. hydrofluoric acid
36. phosphoruspentachloride
(6)
37. water
(3)
(3)
(4/6)
5) a
38. fluorine gas
(6)
39. carbon monoxide
40. magnesium bromide
(1)
41. diamond
42. potassium chloride
(1)
(2)
====================
43. sulfate ion
Tetrahedral/Nonpolar
44. nitrite ion
Bent/Polar
45. phosphorus trichloride
Trigonal Pyramid/Polar
46. carbon monoxide
Linear, Polar
(4)
47. boron trifluoride
Trigonal Planar/Nonpolar
48. beryllium chloride
Linear, Nonpolar
49. selenium hexafluoride
Octahedral/Nonpolar
50. sulfite ion
Trigonal Planar/Nonpolar
51. Explain why the Halogen family starts as gas at room temperature and proceeds from gas to liquid to solid as
you go down the group.
Increasing Dispersion forces due to increased number of electrons leads to more attraction, more compact
state of matter.
52. Why are ionic compounds soluble in water?
Water is polar, meaning it has two regions of opposite charge. Polar ends of water molecules attract
opposite ions and “carry” them into solution.
53. Explain why covalent compounds tend to have low melting points. Covalent compounds have weak,
intermolecular forces (5% the strength of covalent bonds) attracting them together, which means it
takes less energy to overcome these attractions and separate the molecules enough for them to move as
a liquid.