Follow the instructions given for each section of this worksheet. You will need your periodic table, a chart of common polyatomic ions, and your wits to complete this homework.

Part I

1. How do the numbers of protons, neutrons, or electrons change when an atom becomes a cation?
2. How do the numbers of protons, neutrons, or electrons change when an atom becomes an anion?
3. Explain why atoms never lose or gain protons when they become ions.
4. Do non-metals tend to form cations or anions when they become monatomic ions?
5. Do metals tend to form cations or anions when they become monatomic ions?
6. Can a metal form an ionic compound with another metal? Why or why not?
7. Can a non-metal form an ionic compound with another non-metal? Why or why not?
8. What is the difference between a compound and an element?

9. What is a diatomic molecule?
10. Which elements exist in pure form as diatomic molecules? (Remember, you must memorize these!)
11. What are some compounds that are diatomic molecules?
12. How do electrolytes differ from non-electrolytes in their behavior when they dissolve in water?
13. What is an allotrope? Give some examples.
14. Compare and contrast the types of elements found in the chemical formulas of molecular compounds and ionic compounds.

Part II

For each of the following ions write down the name of the ion and the total number of p⁺ and e^-. For example, sodium ion: Na⁺ has 11 p⁺, 10 e^-.

13. K⁺
14. Fe²⁺
15. N^3-

16. Sr²⁺
17. Fe³⁺
18. O^2-

Part III

(a) Write the ionic form of each of the following elements, showing the charge you would expect it to have based on its location in the periodic table. (b) Then build a compound from those ions, writing a chemical formula. Also, (c) write the name of the compound. Remember, the total positive and negative charges must be equal so that the compound is neutrally charged.

19. Sodium, Iodine (example)
         Na⁺    I^-    NaI    Sodium Iodide
20. Calcium, Sulfur
21. Aluminum, Chlorine

22. Barium, Oxygen
23. Potassium, Sulfur
24. Strontium, Nitrogen

Part IV

Name the following compounds. Ionic compounds are on the left, molecular on the right.

25. AgNO₃
26. BaCrO₄
27. Mg(OH)₂
28. ZnSO₄
29. K₂CO₃
30. Pb(NO₃)₂
31. MnCl₂
32. NiS
33. AlH₃

34. PCl₅
35. SF₄
36. SF₆
37. PCl₃
38. H₂O
39. Si₃N₄
40. O₂F₂
41. ClF₃
42. AsI₃

Part V

Write formulas for the following compounds. Ionic compounds are on the left, molecular on the right.

43. Aluminum Fluoride
44. Mercury(II) Sulfate
45. Lead(IV) Oxide
46. Calcium Phosphate
47. Copper(I) Oxide
48. Copper(II) Oxide
49. Lead(II) Carbonate

50. Carbon Monoxide
51. Phosphorus Pentachloride
52. Dinitrogen Tetrasulfide
53. Iodine Monobromide
54. Xenon Tetrafluoride
55. Sulfur tetraiodide
56. Carbon disulfide