1. Compounds and Their Bonds
Valence Electrons
Ions and the Octet Rule

2. Chemical Bonds Attraction between two or more atoms
Interaction between valence electrons
Ionic bonds
Covalent bonds

3. Valence Electrons Electrons in the highest (outer) electron level
Have most contact with other atoms
Known as valence electrons
Outer shelI of noble gases the outer shell contains 8 valence electrons (except He = 2)
Example: Ne 2, 8
Ar 2, 8, 8

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 :
       

5. Electron Dot Formulas A. X would be the electron dot formula for
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

6. 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

7. 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

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 1 metals  ion 1+
Group 2 metals  ion 2+
Group 3 metals  ion 3+

9. Formation of Sodium Ion
Sodium atom Sodium ion
Na  – e  Na +
( = Ne)
11 p p+
11 e e-

10. Formation of Magnesium Ion
Magnesium atom Magnesium ion 
Mg  – 2e  Mg2+
(=Ne)
12 p p+
12 e e-

11. Some Typical Ions with Positive Charges (Cations)
Group 1 Group 2 Group 3
H+ Mg2+ Al3+
Li+ Ca2+
Na+ Sr2+
K+ Ba2+

12. Octet Rule Understanding
A. Number of valence electrons in aluminum
1) 1 e ) 2 e ) 3 e-
B. Change in electrons for octet
1) lose 3e ) gain 3 e ) gain 5 e-
C. Ionic charge of aluminum
1) ) ) 3+

13. 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+

14. Ion Charges 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-

15. 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-

16. More Octet Rule A. Why does Ca form a Ca2+ ion?
B. Why does O form O2- ion?

17. Solution A. Why does Ca form a Ca2+ ion?
Loses 2 electrons to give octet
(like Ar, isoelectronic)
B. Why does O form O2- ion?
Gains 2 electrons to give octet
e (like Ne, isoelectronic)

18. Ions from Nonmetal Ions
In ionic compounds, nonmetals in 15, 16, and 17 gain electrons from metals
Nonmetal add electrons to achieve the octet arrangement
Nonmetal ionic charge:
3-, 2-, or 1-

19. Fluoride Ion     1 - : F  + e : F :     2-7 2-8 (= Ne)
unpaired electron octet
   
: F  e : F :
   
(= Ne)
9 p p+
9 e e-
ionic charge

20. Octet Rule & Nomenclature
Complete the names of the following ions:
N3 O2 F
nitride __________ fluoride
P3 S2 Cl
___________ __________ _________
Br 
_________ I
iodide ion

21. Solution 15 16 17 N3 O2 F nitride oxide fluoride P3 S2 Cl
N3 O2 F
nitride oxide fluoride
P3 S2 Cl
phosphide sulfide chloride
Br 
bromide