CHM1045
Fall 2000
Dr. Michael Blaber

Exam #4 Study Guide

Tuesday December 12 2000

1. General Information:

The exam is worth 100 points and covers chapters 9-10 of your text. There will be 11 questions. The number of points per question is as follows. THERE WILL ALSO BE A 10 POINT EXTRA CREDIT PROBLEM INCLUDED AT THE BACK OF THE EXAM. The examination time is 2 hours. This exam is a typical 1 hour exam, thus, there is time for an extra credit problem.

2. What to study

You are responsible for all material covered in chapters 9-10, as well as information covered in the lectures. Please pay special attention to the following:

• Understand how to use Lewis Structures to show the movement of electrons for chemical reactions that form ionic compounds
• Be prepared to draw Lewis Structures of simple ABn type molecules if given the molecular formula
• Know how to draw resonance Lewis Structures
• Be able to determine formal charges on atoms if provided the Lewis Structure
• Understand how and when you can draw Lewis Structures for central atoms with an expanded octet of electrons
• Be able to calculate reaction enthalpies if provided bond dissociation energies
• Be able to predict valence electron geometries and resulting molecular geometries from a Lewis Structure
• Understand which molecular geometries will result in an overall molecular dipole (if bonds are polar covalent) and which ones will not (even if bonds are polar covalent)
• Be able to draw an orbital diagram for an atom, from a Lewis Structure, that shows how the valence orbitals hybridize and are populated with electrons
• Know the characteristic bond angles for the different types of molecular geometries
• Be able to predict, using a table of electronegativities, whether bonds will be ionic, polar covalent, or non-polar covalent
• Be able to diagram a Born-Haber cycle enthalpy diagram if provided relevant enthalpies, and be able to determine lattice energies from such a diagram