1.1 What is Chemistry?

http://www.ck12.org Chapter 9. Covalent Bonding

Lesson Summary

• Valence shell electron pair repulsion (VSEPR) theory is a technique for predicting the molecular geometry of
  a molecule. A molecule’s shape provides important information that can be used to understand its chemical
  and physical properties.


• According to VSEPR, covalent bonds and lone pairs distribute themselves around a central atom in such a
  way as to maximize their distance from each other.


• Electron domain geometries are based on the total number of bonds and lone pairs, while molecular geometries
  look only at the arrangements of atoms and bonding pairs.

Lesson Review Questions

1. What is the basic principle of VSEPR theory?


2. How many covalent bonds would there be attached to a central atom in the following configurations:
   a. tetrahedral
   b. octahedral
   c. trigonal planar
   d. linear


3. What is the difference between the electron domain geometry and the molecular geometry?


4. How do lone pairs act differently than bonding pairs in terms of electron repulsion?


5. Using the VSEPR method, predict the molecular geometries (including bond angles) for each of the following
   molecules:
   a. SF 2
   b. PBr 3
   c. AlCl 3
   d. TeCl 6
   e. HCN

Further Reading / Supplemental Links

Video on VSEPR theory: http://www.youtube.com/watch?v=FhVkCH9COZo

Possible shapes of molecules according to VSEPR theory: http://www.youtube.com/watch?v=i3FCHVlSZc4

Points to Consider

• How might molecular geometry affect how molecules interact with one another?