1. Chapter Exercises: Chemical Bonds (I):
Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT: 
1. The chlorine atom gains seven electrons when it becomes an ion.
2. Ionic compounds conduct electricity better in the molten state
than in the solid state.
3. During the formation of the compound NaCl, one electron is
transferred from a sodium atom to a chlorine.
4. A piece of metal consists of closely packed cations surrounded by
mobile valence electrons.
5. A molecule contains two atoms. NT AT AT AT ST

2. Fill in the word(s) that will make each statement true:
6. The electrons in the highest occupied energy level of an atom are called the
_____________ electrons.
7. The _______ rule states that atoms in compounds tend to have the electron
configuration of a noble gas.
8. An oxygen atom attains a stable electron configuration by_________ two
electrons.
9. Atoms and ions with _______ electrons in their highest energy levels are very
stable.
10. Potassium forms a cation by attaining a _______ electron configuration with
8 outer electrons.
11. _______ tend to lose electrons when they react to form compounds.
12. An _______ is any atom or group of atoms with a negative charge.
13. The lowest whole-number ratio of ions in an ionic compound is known as a
__________________.
valence
octet
Gaining or sharing 8
stable
Metals
anion
formula unit

3. Choose the best answer:
14. A bond in which each atom contributes two electrons is
a. a double covalent bond. c. a polar covalent bond.
b. an ionic bond d. a coordinate covalent bond.
15. The electron dot structure for hydrogen sulfide, H2S, is
a b c d.
16. Which electron dot structure represents a nonpolar molecule?
17. Bond dissociation energy
a. is the energy required to break a single bond.
b. of a C — H bond is high.
c. of a C — C bond is high.
d. all of the above

4. 18. A covalent bond formed between two elements that have an
electronegativity difference of 1.6 would be
a. a nonpolar bond c. a moderately polar bond.
b. a very polar bond d. an ionic bond.
19. You would expect a bond formed between a silicon atom and an
oxygen atom to be
a. an ionic bond c. a polar covalent bond.
b. a coordinate covalent bond. d. a nonpolar covalent bond.

5. Chapter Exercises: Chemical Bonds (II): e. Electron dot structure
A. Matching:
Column A
1. Compound composed of cations and anions
2. The forces of attraction that bind oppositely charged ions together
3. Lowest whole-number ratio of ions in an ionic compound
4. A depiction of the valence electrons as dots around the symbol for an element
5. A mixture of two or more elements, at least one of which is a metal
6. The attraction of the free-floating valence electrons for the positively charged metal ions
7. Ions of the halogen atoms
8. The electron(s) in the highest occupied energy level of an atom
9. Atoms in a compound tend to have the electron configuration of a noble as.
10. Shows the kinds and numbers of atoms in the smallest representative unit of a substance
f. Ionic compound
g. Ionic bonds
d. Formula unit
e. Electron dot structure
b. Alloy
j. Metallic bond
a. Halide ions
i. Valence elec.
c. Octet rule
h. Chemical formula

6. B. Multiple Choices:
11. All the elements in a particular group of the periodic table have the same number of
a. electrons. b. energy levels c. valence electrons. d. protons.
12. What is the number of valence electrons in an atom of Al?
a b c d. 8
13. Among the following, the element with six valence electrons is
a. C b. Cs c. O. d. Ne.
14. The electron dot structure for Cl is
a b c d.

7. 15. In general, metals react by:
a. losing valence electrons.
b. gaining valence electrons.
c. sharing valence electrons.
d. sometimes gaining and sometimes losing valence electrons.
16. An ion of K has the same electron configuration as
a. Na c. Ar.
b. Ca d. Kr.
17. The outer energy level configuration for O2– is
a. 2s c. 2s2 2p5.
b. 2s22p d. 2s2 2p6.

8. 18. The general electron dot structure could represent
a. Li c. B.
b. Na d. N.
19. The chemical properties of an element are largely determined by its
a. number of energy levels.
b. period number.
c. number of protons.
d. number of valence electrons.
20. Which of the following has a noble gas electron configuration?
a. Na c. Al3+
b. Mg+ d. Br

9. 21. Atoms of Ca S would be expected to react in a ratio of
a. 1:1. and c. 2:1.
b. 1: d. 3:1.
22. The chemical formula for the ionic compound formed when elements of Ca and N react is
a. CaN. c. Ca3N2.
b. Ca2N d. Ca5N2.
23. In general, ionic compounds
a. are amorphous solids at room temperature.
b. conduct electricity when in the solid state.
c. conduct electricity when they are dissolved in water.
d. all of the above

10. 24. Metals typically are
a. good conductors of electrical current.
b. malleable.
c. ductile.
d. all of the above
25. Which of the following is an anion?
a. O2– c. Al3+
b. Mg d. H  
26. The nonmetals in Groups 5A, 6A, and 7A
a. lose electrons when they form ions.
b. form positively charged ions.
c. form ions with charges of 3–, 2–, and 1–, respectively.
d. form ions with a numerical charge equal to their group number.

11. 27. Among the following, which atom is most likely to form an ion with a charge of 2+?
a. O c. Al
b. Na d. Ca
C. True – False:
Classify each of these statements as AT, ST or NT:
28. Among Groups 1A and 2A, the group number of each element is equal to
the number of valence electrons in an atom of that element.
 29. Alloys are mixtures with at least one metal.
 30. In general, atoms react in an attempt to attain the electron configuration
of a noble gas.
31. The loss of valence electrons from an atom produces an anion. AT AT AT NT

12. 32. Nonmetals typically react by gaining electrons to attain noble gas electron configurations.
33. Ions have more electrons than the atoms from which they were formed.
34. In the formation of an ionic compound, a single electron is transferred from one atom to the other.
35. The atoms of Group 7A elements gain electrons when they form ions.
36. An atom with a positive charge is an anion.
37. The ionic charge of an element in Group 6A is 2–. ST ST ST AT NT ST

13. D. Questions: Na, F. Mg, Cl. Ca, S. Al, O.
E. Essay:
Calcium is located in Group 2 A, so it has 2 valence electrons & will lose these e-, which will be gained by Fluorine; two fluorine atoms are required because it is in Group 7 A, its has 7 valence e-, so it is able to accept only one electron.

14. Chapter Exercises: Chemical Bonds (III):
a. shows the kinds and numbers of atoms present in a molecule of a compound
b. chemical formula that shows the arrangement of atoms in molecules and polyatomic ions
c. a covalent bond between two atoms of different electronegativities in which the bonding electrons are not shared equally
d. a covalent bond formed by the equal sharing of bonding electrons by two atoms
e. a covalent bond involving two pairs of electrons; each atom donates one pair of electrons to the bond
f. a covalent bond in which three pairs of electrons are shared by two bonded atoms
g. substance in which all of the atoms are covalently bonded to each other
h. force that occurs when a hydrogen atom that is covalently bonded to a very electronegative atom is also weakly bonded to an unshared pair of electrons in the same or a nearby molecule
4. Molecular formula
5. Structural formula
6. Polar bond
1. Nonpolar covalent bond
3. Double covalent bond
7. Triple covalent bond
8. Network solid
2. Hydrogen bond

15. B. Multiple choices:
9. Which of the following exists as a diatomic molecule?
a. He c. Cl
b. Ar d. Na
10. The diatomic molecule among the following that contains a single covalent bond is
a. F c. N2.
b. O d. O2.
11. Atoms share electrons in order to acquire the electron configurations of
a. alkali metals c. halogens.
b. alkaline earth metals d. noble gases.
12. In Cl2, what is the total number of unshared pairs of electrons?
a c. 4
b d. 6

16. B. Multiple choices:
13. The diatomic molecule among the following that contains a triple covalent bond is
a. O c. H2.
b. Cl d. N2.
14. In the N2 molecule, what is the number of unshared pairs of electrons in each nitrogen atom?
a c. 3
b d. 4
15. The covalent molecule among the following is
a. NaCl c. CaO.
b. NH d. KF.
16. How many single covalent bonds are there in a molecule of CH4?
a c. 3
b d. 4

17. B. Multiple choices:
17. How many double covalent bonds are there in a molecule of CO2?
a c. 3
b d. 4
18. The molecule among the following that contains only one single covalent bond is
a. NH c. HI.
b. N d. H2O.
19. In forming the molecule HF, the F atom attains the electron configuration of
a. He c. Ar.
b. Ne d. Cl.
20. Which of the following contains a polar covalent bond?
a. O c. CaO
b. MgCl2 d. HF

18. B. Multiple choices:
21. What type of bond would be expected in a molecule of LiF?
a. ionic bond c. nonpolar covalent bond
b. polar covalent bond d. none of the above
22. Among the following molecules, the one containing the most polar bond is
a. HF c. HBr.
b. HCl d. H2O.
23. The polar molecule among the following is
a. CCl c. H2O.
b. CO d. N2.

19. B. Multiple choices:
24. The strongest intermolecular attractive forces from among those listed are
a. dispersion forces c. hydrogen bonds.
b. dipole interactions d. cannot be determined
25. The melting and boiling points of most molecular compounds are
a. lower than those of most ionic compounds.
b. about the same as those of most ionic compounds.
c. higher than those of most ionic compounds.
d. sometimes higher and sometimes lower than those of most ionic compounds.
26. Network solids
a. have low melting points. c. are extremely hard.
b. have low boiling points. d. are generally ductile.

20. C. Questions:
27. Draw structural formulas for the following substances.
a. Br b. N c. CO2
28. The following covalent molecules have only single covalent bonds. Draw an electron dot structure for each one.
a. HBr b. H2O c. PCl3
29. State whether the following compounds contain polar covalent bonds, nonpolar covalent bonds, or ionic bonds. (You may refer to the table of electronegativities)
a. KF b. SO c. NO d. HBr
Br– Br
N = N
O = C = O
Cl P Cl Cl
H Br
H O O H
Polar covalent
Polar covalent
Ionic
Polar covalent
(moderately)
(moderately)
(very)