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

2. 2 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 Octet Rule

3. 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.

4. 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+ Copyright © 2009 by Pearson Education, Inc.

5. 5 Formation of a Sodium Ion, Na +

6. 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+ 2, 8 Copyright © 2009 by Pearson Education, Inc.

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

8. 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+ Copyright © 2009 by Pearson Education, Inc.

9. 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 +.

10. 10 Solution A. The number of valence electrons in aluminum is 3) 3 e -. B. The change in electrons for octet requires a 1) loss of 3e -. C. The ionic charge of aluminum is 3) 3+. D. The symbol for the aluminum ion is 1) Al 3+.

11. 11 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.

12. 12 Formation of a Chloride, Cl - Chlorine achieves an octet by adding an electron to its valence electrons.

13. 13 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 – Copyright © 2009 by Pearson Education, Inc.

14. 14 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-

15. 15 Some Ionic Charges

16. 16 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-. Learning Check

17. 17 A. The number of valence electrons in sulfur is 2) 6e -. B. The change in electrons for octet requires a 2) gain of 2e -. C. The ionic charge of sulfur is 2) 2-. Solution