1. Chapter 4 Compounds and Their Bonds
4.1 Valence Electrons
4.2 Octet Rule and Ions
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2. LecturePLUS Timberlake
Chemical Bonds
Attraction between two or more atoms
Interaction between valence electrons
Ionic bonds
Covalent bonds
Metallic bonds
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3. LecturePLUS Timberlake
Valence Electrons
Electrons in the highest (outer) electron level
Have most contact with other atoms
Outer shells of noble gases contain 8 valence electrons (except He = 2)
Example: Ne 2, 8
Ar 2, 8, 8
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4. Electron Dot Structures
Symbols of atoms with dots to represent the valence-shell electrons
1A A 3A A A A 7A A
H He:
          
Li Be  B   C   N   O  : F  :Ne :
       
          
Na Mg  Al  Si  P S :Cl  :Ar :
       
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5. LecturePLUS Timberlake
Learning Check 
A. X would be the electron dot formula for
1) Na 2) K 3) Al
 
B  X  would be the electron dot formula
1) B 2) N 3) P
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6. LecturePLUS Timberlake
Solution 
A. X would be the electron dot formula for
1) Na 2) K
 
B  X  would be the electron dot formula
2) N 3) P
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7. LecturePLUS Timberlake
Octet Rule
An octet in the outer shell makes atoms stable
Electrons are lost, gained or shared to form an octet
Unpaired valence electrons strongly influence bonding
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8. Metals forming ions- Cations (cats have paws-pos)
Metals lose electrons to match the number of valence electrons of their nearest noble gas
Positive ions form as a result
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9. Formation of Sodium Ion
Sodium atom Sodium ion
Na  – e  Na +
( = Ne)
11 p p+
11 e e-
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10. Formation of Magnesium Ion
Magnesium atom Magnesium ion 
Mg  – 2e  Mg2+
(=Ne)
12 p p+
12 e e-
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11. Some Typical Ions with Positive Charges (Cations)
Group 1A Group 2A Group 3A
H+ Mg2+ Al3+
Li+ Ca2+
Na+ Sr2+
K+ Ba2+
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12. LecturePLUS Timberlake
Learning Check
A. Number of valence electrons in aluminum
1) 1 e ) 2 e- 3) 3 e-
B. Change in electrons for octet
1) lose 3e ) gain 3 e ) gain 5 e-
C. Ionic charge of aluminum
1) ) ) 3+
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13. LecturePLUS Timberlake
Solution
A. Number of valence electrons in aluminum
3) 3 e-
B. Change in electrons for octet
1) lose 3e-
C. Ionic charge of aluminum
3) 3+
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14. LecturePLUS Timberlake
Learning Check
Give the ionic charge for each of the following:
A. 12 p+ and 10 e-
1) 0 2) 2+ 3) 2-
B. 50p+ and 46 e-
1) 2+ 2) 4+ 3) 4-
C. 15 p+ and 18e-
2) ) 3- 3) 5-
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15. LecturePLUS Timberlake
Solution
Give the ionic charge for each of the following:
A. 12 p+ and 10 e-
2) 2+
B. 50p+ and 46 e-
2) 4+
C. 15 p+ and 18e-
2) 3-
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16. LecturePLUS Timberlake
Learning Check
A. Why does Ca form a Ca2+ ion?
B. Why does O form O2- ion?
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17. LecturePLUS Timberlake
Solution
A. Why does Ca form a Ca2+ ion?
Loses 2 electrons to give octet
(like Ar)
B. Why does O form O2- ion?
Gains 2 electrons to give octet
e (like Ne)
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18. Nonmetal Ions-anions (a negative ion)
Nonmetals in 5A, 6A, and 7A gain electrons from metals, become negatively charged
Nonmetal ionic charge:
3-, 2-, or 1-
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19. LecturePLUS Timberlake
Fluoride Ion
unpaired electron octet
   
: F  e : F :
   
(= Ne)
9 p p+
9 e e-
ionic charge
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20. LecturePLUS Timberlake
Learning Check
Complete the names of the following ions:
5A A A
N3 O2 F
nitride __________ fluoride
P3 S2 Cl
___________ __________ _________
Br 
_________
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21. LecturePLUS Timberlake
Solution
5A A A
N3 O2 F
nitride oxide fluoride
P3 S2 Cl
phosphide sulfide chloride
Br 
bromide
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