(©2002, François G. Amar, All rights reserved)

Summary for Week 10

Reading:

For this week: Chapter 8.3-8.9

A look ahead: Prelim on Monday, November 11, start Chapter 7

Homework problems:

Beginning of Chapter 8: 8.2, 8.7, 8.9, 8.17, 8.23, 8.27, 8.32, 8.33, 8.34, 8.37

End of Chapter 8: 8.41, 8.45, 8.47, 8.53, 8.58, 8.60

Key concepts and equations:

Electronegativity concept (see pp 273-274)

         Ionic, covalent and metallic bonds      

Lewis symbols and the octet rule
      
      Ionic bonding and lattice energy
            
      		Eionic = kQ1Q2/d        (k=8.99x109 J-m/C2)
      
         Electron configurations of common atomic ions obey the octet rule
            

Cations are smaller than neutral parents

	Anions are larger than neutral parents
      
      Covalent bonding (sharing electrons): electron pair bond.
      
	Drawing Lewis dot structures (rules on p 269)
      
	Bond polarity (unequal sharing)
      
	Electronegativity
      
	Formal charge (the limiting case of perfect sharing) 
		the Lewis structure with smaller formal charges is preferred
      
	Resonance structures
      
	Exceptions to the octet rule 

odd number of electrons
(>8) 3rd row elements
(<8) B and Be

      
	Bond strength and bond length
      
	Bond enthalpies and estimating enthalpies of reaction
      
      	  DHrxn  ~    S(bond enthalpies of bonds broken) 

-   S (bond enthalpies of bonds formed)