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

Summary for Week 11

Reading:

For this week: Finish Chapter 8 (8.9--bond enthalpy); exam on Monday

Chapter 7 (sections 7.1-7.3) and begin Chapter 9

A look ahead: End of Chapter 9

Homework problems:

Chapter 8: see Week 10 summary

Chapter 7: 7.3, 7.7, 7.10, 7.12, 7.19, 7.23, 7.25, 7.27, 7.29

Chapter 9: 9.2, 9.9, 9.11, 9.13, 9.16, 9.19, 9.25, 9.29, 9.32, 9.34

9.39, 9.41, 9.42, 9.45, 9.47, 9.51, 9.69

Key Concepts and Equations

Molecular shapes (Chapter 9)

triangles, tetrahedrons, and other shapes

      
	VSEPR model
      
	electron pairs and repulsion
	nonbonding pairs and multiple bonds
      
	expanded valence shells (3rd row nonmetals  like P, S, Cl)
      
	more than one "central" atom   --->  organic chemistry!
      
	bond polarity and molecular dipole moment
      
	orbital overlap in covalent bonding of diatomics
      
	hybridization (electron promotion and orbital mixing)
      
	multiple bonds
      
	molecular orbitals for diatomics (bond order)

Chemical Periodicity (Chapter 7)

Atomic size; size of ions

Ionization energy of a reaction such as, Na --> Na⁺ + e^- ; periodic trends

	Electron affinity (usually exothermic)
		Cl + e-  --> Cl-    DE = -349 kJ/mol  =  electron affinity or EA of Cl

	    however

		N + e-  --> N-      D E > 0 therefore the negative ion, N-,  is unstable in the gas phase