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
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3. LecturePLUS Timberlake
Valence Electrons
Electrons in the highest (outer) electron level
Have most contact with other atoms
Known as valence electrons
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. Formation of Ions from Metals
Ionic compounds result when metals react with nonmetals
Metals lose electrons to match the number of valence electrons of their nearest noble gas
Positive ions form when the number of electrons are less than the number of protons
Group 1A metals  ion 1+
Group 2A metals  ion 2+
Group 3A metals  ion 3+
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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. Ions from Nonmetal Ions
In ionic compounds, nonmetals in 5A, 6A, and 7A gain electrons from metals
Nonmetal add electrons to achieve the octet arrangement
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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