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45. What is the formula for the sulfate ion? 5. Is there a relationship between the number of valence electrons
–
a. (HSO 4 ) and how many covalent bonds an atom can form? Explain.
2–
b. (SO 4 ) 6. Write electron dot formulas for molecules formed when
2–
c. S hydrogen combines with (a) chlorine, (b) oxygen, and (c) carbon.
2–
d. (SO 3 )
7. Sodium fluoride is often added to water supplies to strengthen
46. The correct name for the compound NaNO 3 is teeth. Is sodium fluoride ionic, covalent, or polar covalent?
a. sodium nitrogen trioxygen. Explain the basis of your answer.
b. sodium nitrate.
8. What is the modern systematic name of a compound with the
c. sodium nitrite.
formula (a) SnF 2 and (b) PbS?
d. sodium nitrogen trioxide.
9. What kinds of elements are found in (a) ionic compounds with a
47. How many valence electrons does the element nitrogen (N)
name ending with an -ide suffix and (b) covalent compounds
have?
with a name ending with an -ide suffix?
a. 3
10. Why is it necessary to use a system of Greek prefixes to name
b. 7
binary covalent compounds?
c. 5
d. 14 11. What are variable-charge ions? Explain how variable-charge ions are
identified in the modern systematic system of naming compounds.
48. A nonmetal atom combines with a second nonmetal atom. The
first nonmetal atom 12. What is a polyatomic ion? Give the names and formulas for
a. gains electrons. several common polyatomic ions.
b. loses electrons. 13. Write the formula for magnesium hydroxide. Explain what the
c. remains neutral. parentheses mean.
d. shares electrons with the second nonmetal atom. 14. What is a double bond? A triple bond?
49. Polar covalent bonds result when the electronegativity difference
between the two atoms in the bond is
a. 1.7 and greater. FOR FURTHER ANALYSIS
b. between 0.5 and 1.7.
1. What are the significant similarities and differences between a
c. less than 0.5.
physical change and a chemical change?
d. equal to 0.
2. Analyze how you would know for sure that a pure substance you
50. What is the formula for the compound aluminum bromide?
have is an ionic and not a covalent compound.
a. AlBr 2
3. Make up an explanation for why ionic compounds are formed
b. AlBr 3
when a metal from the left side of the periodic table reacts with a
c. Al 2 Br 3
d. Al 3 Br nonmetal from the right side, but covalent bonds are formed
between nonmetallic elements on the right side of the table.
51. The combination of nonmetals with nonmetals forms
a. covalent compounds. 4. Describe how you would teach another person how to name
b. metallic compounds. ionic and covalent compounds.
c. ionic compounds.
d. no compounds.
INVITATION TO INQUIRY
Answers
1. d 2. b 3. a 4. c 5. a 6. c 7. c 8. c 9. a 10. a 11. b 12. b 13. a 14. c Seeing the Light
15. c 16. a 17. a 18. b 19. c 20. c 21. b 22. a 23. b 24. c 25. d 26. a
Dissolving an ionic compound in water results in ions being pulled
27. b 28. a 29. c 30. b 31. c 32. b 33. a 34. b 35. d 36. c 37. b 38. a
from the compound to form free ions. A solution that contains ions will
39. c 40. b 41. b 42. b 43. c 44. c 45. b 46. b 47. c 48. d 49. b 50. b
conduct an electric current, so electrical conductivity is one way to test
51. a
a dissolved compound to see whether it is an ionic compound.
Make a conductivity tester from a 9 V battery and a miniature
QUESTIONS FOR THOUGHT Christmas tree bulb with two terminal wires. Sand these wires to make
a good electrical contact. Try testing (1) dry baking soda, (2) dry table
1. Describe how the following are alike and how they are different: salt, and (3) dry sugar. Test solutions of these substances dissolved in
(a) a sodium atom and a sodium ion and (b) a sodium ion and a distilled water. Test pure distilled water and rubbing alcohol. Explain
neon atom.
which contains ions and why.
2. What is the difference between a polar covalent bond and a
nonpolar covalent bond?
3. What is the difference between an ionic and covalent bond?
What do atoms forming the two bond types have in common?
4. What is the octet rule?

9-21 CHAPTER 9 Chemical Bonds 249