1. Chapter 4 Compounds and Their Bonds 4.1 Octet Rule and Ions 1 Copyright © 2009 by Pearson Education, Inc.

2. Octet Rule An octet is 8 valence electrons. is associated with the stability of the noble gases. He is stable with 2 valence electrons (duet). valence electrons He 2 2 Ne 2, 8 8 Ar 2, 8, 8 8 Kr 2, 8, 14, 8 8 2

3. Ionic and Covalent Bonds Atoms that are not noble gases form octets to become more stable. by losing, gaining, or sharing valence electrons. by forming ionic bonds or covalent bonds. 3

4. Metals Form Positive Ions Metals form positive ions by a loss of their valence electrons. with the electron configuration of the nearest noble gas. that have fewer electrons than protons. Group 1A metals ion 1+ Group 2A metals ion 2+ Group 3A metals ion 3+ 4 Copyright © 2009 by Pearson Education, Inc.

5. Formation of a Sodium Ion, Na + 5

6. Charge of Sodium Ion, Na + With the loss of its valence electron, the sodium ion has a 1+ charge. Na atom Na + ion 11p + 11e - 10e - 0 1+ 6 2, 8 Copyright © 2009 by Pearson Education, Inc.

7. Formation of Mg 2+ Magnesium achieves an octet by losing its two valence electrons. 7

8. Charge of Magnesium Ion, Mg 2+ With the loss of two valence electrons, magnesium forms a positive ion with a 2+ charge. Mg atomMg 2+ ion 12p + 12p + 12e- 10e - 0 2+ 8 Copyright © 2009 by Pearson Education, Inc.

9. Learning Check A. The number of valence electrons in aluminum is 1) 1e -. 2) 2e -.3) 3e -. B. The change in electrons for octet requires a 1) loss of 3e -. 2) gain of 3e -. 3) a gain of 5e -. C. The ionic charge of aluminum is 1) 3-.2) 5-.3) 3+. D. The symbol for the aluminum ion is 1) Al 3+.2) Al 3-.3) Al +. 9

10. Formation of Negative Ions In ionic compounds, nonmetals in Groups 5A (15), 6A (16) and 7A (17) achieve an octet arrangement by gaining electrons. form negatively charged ions with 3-, 2-, or 1- charges. 10

11. Formation of a Chloride, Cl - Chlorine achieves an octet by adding an electron to its valence electrons. 11

12. Charge of a Chloride Ion, Cl - By gaining 1 electron, the chloride ion has a 1- charge. Chlorine atom, Cl Chloride ion, Cl – 17p + 17p + 17e - 18e - 0 1 – 12 Copyright © 2009 by Pearson Education, Inc.

13. Ionic Charge from Group Numbers The charge of a positive ion is equal to its Group number. Group 1A(1) = 1+ Group 2A(2) = 2+ Group 3A(3) = 3+ The charge of a negative ion is obtained by subtracting 8 or 18 from its Group number. Group 6A(16) = 6 - 8 = 2- or 16 - 18= 2- 13

14. Some Ionic Charges 14

15. Learning Check A. The number of valence electrons in sulfur is 1) 4e -. 2) 6e -. 3) 8e -. B. The change in electrons for octet requires a 1) loss of 2e -. 2) gain of 2e -. 3) a gain of 4e -. C. The ionic charge of sulfur is 1) 2+. 2) 2-. 3) 4-. 15

16. Chapter 4 Compounds and Their Bonds 4.2 Ionic Compounds 16 Copyright © 2009 by Pearson Education, Inc.

17. Ionic Compounds Ionic compounds consist of positive and negative ions. have attractions called ionic bonds between positively and negatively charged ions. have high melting and boiling points. are solid at room temperature. 17

18. Salt Is An Ionic Compound Sodium chloride or “table salt” is an example of an ionic compound. 18

19. Ionic Formulas An ionic formula consists of positively and negatively charged ions. is neutral. has charge balance. total positive charge = total negative charge The symbol of the metal is written first, followed by the symbol of the nonmetal. 19

20. Charge Balance for NaCl, “Salt” In NaCl, a Na atom loses its valence electron. a Cl atom gains an electron. the symbol of the metal is written first, followed by the symbol of the nonmetal. 20

21. Charge Balance in MgCl2 In MgCl 2, a Mg atom loses 2 valence electrons. two Cl atoms each gain 1 electron. subscripts indicate the number of ions needed to give charge balance. 21 Copyright © 2009 by Pearson Education, Inc.

22. Charge Balance in Na 2 S 22 In Na 2 S, two Na atoms lose 1 valence electron each. one S atom gains 2 electrons. subscripts show the number of ions needed to give charge balance. Copyright © 2009 by Pearson Education, Inc.

23. Writing Ionic Formulas from Charges Charge balance is used to write the formula for sodium nitride, a compound containing Na + and N 3−. Na + 3Na + + N 3− = Na 3 N Na + 3(+1) + 1(3-) = 0 23

24. Formula from Ionic Charges Write the ionic formula of the compound with Ba 2+ and Cl . Write the symbols of the ions. Ba 2+ Cl  Balance the charges. Ba 2+ Cl  two Cl - needed Cl  Write the ionic formula using a subscript 2 for two chloride ions. BaCl 2 24

25. Learning Check Select the correct formula for each of the following ionic compounds. A. Na + and O 2- 1) NaO 2) Na 2 O3) NaO 2 B. Al 3+ and Cl - 1) AlCl 3 2) AlCl 3) Al 3 Cl C. Mg 2+ and N 3- 1) MgN 2) Mg 2 N 3 3) Mg 3 N 2 25

26. Chapter 4 Compounds and Their Bonds 4.3 Naming and Writing Ionic Formulas 26 Copyright © 2009 by Pearson Education, Inc.

27. Naming Ionic Compounds with Two Elements To name a compound that contains two elements, identify the cation and anion. name the cation first, followed by the name of the anion with an – ide ending. 27

28. Charges of Representative Elements 28 Copyright © 2009 by Pearson Education, Inc.

29. Names of Some Common Ions 29

30. Learning Check Complete the names of the following ions: Ba 2+ Al 3+ K + _________ __________ _________ N 3  O 2  F  _________ __________ _________ P 3  S 2  Cl  _________ __________ _________ 30

31. Examples of Ionic Compounds with Two Elements Formula IonsName cation anion NaClNa + Cl - sodium chloride K 2 SK + S 2- potassium sulfide MgOMg 2+ O 2- magnesium oxide CaI 2 Ca 2+ I - calcium iodide Al 2 O 3 Al 3+ O 2- aluminum oxide 31

32. Learning Check Write the names of the following compounds: 1) CaO___________ 2) KBr___________ 3) Al 2 O 3 ___________ 4) MgCl 2 ___________ 32

33. Learning Check Write the formulas and names for compounds of the following ions: Br − S 2− N 3− Na + Al 3+ 33

34. Transition Metals Form Positive Ions Most transition metals and Group 4 (14) metals form 2 or more positive ions. However, Zn 2+, Ag +, and Cd 2+ form only one ion.

35. Metals That Form More Than One Cation The name of metals with two or more positive ions (cations) use a Roman numeral to identify ionic charge. 35

36. Naming Variable Charge Metals Transition metals with two different ions use a Roman numeral after the name of the metal to indicate ionic charge. 36

37. Naming FeCl 2 To name FeCl 2 : 1. Determine the charge of the cation using the charge of the anion (Cl - ). Fe ion + 2 Cl - = Fe ion + 2- = 0 Fe ion = 2+ 2. Name the cation by the element name and add a Roman numeral in parentheses to show its charge. Fe 2+ = iron(II) 3. Write the anion with an ide ending. FeCl 2 = iron(II) chloride 37

38. Naming Cr 2 O 3 To name Cr 2 O 3 : 1. Determine the charge of cation from the anion (O 2- ). 2 Cr ions + 3 O 2- = 0 2 Cr ions + 3 (2-) = 0 2 Cr ions - 6 = 0 2 Cr ions = 6+ Cr ion = 3+ = Cr 3+ 2. Name the cation by the element name and add a Roman numeral in parentheses to show its charge. Cr 3+ = chromium(III) 3. Write the anion with an ide ending. chromium(III) oxide = Cr 2 O 3 38

39. Learning Check Select the correct name for each. A. Fe 2 S 3 1) iron sulfide 2) iron(II) sulfide 3) iron(III) sulfide B. CuO 1) copper oxide 2) copper(I) oxide 3) copper(II) oxide 39

40. Writing Formulas Write a formula for potassium sulfide. 1. Identify the cation and anion. potassium = K + sulfide = S 2− 2. Balance the charges. K + S 2− K + 2(1+) + 2(1-) = 0 3. 2 K + and 1 S 2− = K 2 S 40

41. Writing Formulas Write a formula for iron(III) chloride. 1. Identify the cation and anion. iron (III) = Fe 3+ (III = charge of 3+) chloride = Cl − 2. Balance the charges. Fe 3+ Cl − Cl − = (3+) + 3(1-) = 0 Cl − 3. 1 Fe 3+ and 3 Cl − = FeCl 3 41

42. Learning Check What is the correct formula for each of the following? A. Copper(I) nitride 1) CuN2) CuN 3 3) Cu 3 N B. Lead(IV) oxide 1) PbO 2 2) PbO 3) Pb 2 O 4 42