This document provides an overview of CHEM 121 General Chemistry II taught by Dr. Wanda Oehrli. It includes the course agenda for the day which is introductions, starting Chapter 11 on intermolecular forces, and reviewing the syllabus. Dr. Oehrli's background is also summarized, including her education in chemistry and work experience in areas like biopharmaceutical development and teaching. Information about office hours, an upcoming reading assignment on intermolecular forces, and the start of the general chemistry lab is also presented.

1. CHEM 121:
General Chemistry II
Dr. Wanda Oehrli (Early)
Welcome back!

2. “All the world is a laboratory to the
inquiring mind”
• Martin H. Fischer
• (1879 - 1962)
• German-American physician and writer
• An education in chemistry and science can
be applied to a broad variety of problems.

3. Today’s Agenda
•
•
•
•
Roll sheet, please sign and note your TEAM #
Introductions
Start Chapter 11
Syllabus

4. Grew up in DeKalb

5. Kalamazoo College & MSU
B.A. Chemistry, 1992
Ph.D. Chemistry, 1997

6. Ph.D. Research
• Optical Sensors
• Funded by the Air Force
• Benzene, Toluene, Zylene
(BTEX) are used to clean jet
engines
• BTEX leach into ground
water
• Bioremediation

7. NRC Postdoctoral Research Fellow
Center for Advanced Research in Biotechnology
and National Cancer Institute
1997-2004
Protein Folding
GroEL GroES
How do heat shock proteins work?
Biopharmaceutical Development of
drugs for cancer based on
antibodies and other biomolecules

8. Teaching 2005-2008 & Ball
Horticultural
Kishwaukee
Beloit
Rock Valley
Elmhurst
Harper
Got Married
Flower seed
germination

9. 2009- Present
MBA – DePaul
Consulting Work
Nanotechnology company in S. Dakota
Green Certification Company in CA
Investment Advisor Firm
Internet Marketing
Back to teaching

10. I want to get to know you!
• Please fill out the info sheet as
thoroughly as possible
• This information will help me get to
know you and shape the course for
your needs

11. Gen. Chem. Lab
• Lab begins next week! January 16!
– Lab Safety and Math Review
• No class of January 20 (MLK Week) & no
lab that week
• Lab resumes week following week

12. Office Hours
My office is Parmer 319
• M,W, F 10:30 -11:30 (meet in 310 if 319 is
occupied)
• Or by appointment (e-mail me)
• Office hours will be posted on the myDU
page each week

13. Pre-Class Reading Assignment
Reading for Friday January 10:
Sections 11.1-11.2
There will be a Reading Quiz at
the beginning of class on Friday!

14. Chapter 11
Intermolecular Forces

15. A Molecular Comparison of Liquids
and Solids
15

16. A Molecular Comparison of Liquids
and Solids
• Converting a gas into a liquid or solid requires
the molecules to get closer to each other:
– cool or compress.
• Converting a solid into a liquid or gas requires
the molecules to move further apart:
– heat or reduce pressure.
• The forces holding solids and liquids together
are called intermolecular forces.

17. Intermolecular Forces

18. Intermolecular Forces
• The covalent bond holding a molecule together is an
intramolecular forces.
• The attraction between molecules is an intermolecular force.
• Intermolecular forces are much weaker than intramolecular
forces
• (e.g. 16 kJ/mol vs. 431 kJ/mol for HCl).
• Ex. Less energy is required to vaporize liquid HCl than
to form an HCl bond
• When a substance melts or boils the intermolecular forces
are broken (not the covalent bonds). When a substance
condenses intermolecular forces are formed.

19. Intermolecular Forces
There are four types of intermolecular forces
(IMF) for covalent molecules:
•
•
•
•
London Dispersion Forces (LD)
Dipole-Dipole (D/D)
Hydrogen bonding (H-bond)
Ion-Dipole (I/D, only in water solutions)
We see evidence of these intermolecular forces as
they affect the boiling point and melting point of
compounds.
– As IMF increase … bp and mp increase

20. Strength of IM Forces
•
•
•
•
London Dispersion Forces (LD)
2-10 kJ/mol
Dipole-Dipole (D/D)
Ion-Dipole (I/D, only in water solutions) 15 kJ/mol
Hydrogen bonding (H-bonding) 5-25 kJ/mol
• First two are called van der Waals

21. Polarity of Molecules
Dipole Moments of Polyatomic Molecules

22. Induced Dipoles or Instantaneous
Dipoles
Neutral molecules and atoms can induce
a charge in each other

23. London Dispersion Forces
The fluctuating charge distribution in an atom can give rise to an
instantaneous dipole moment.
When two atoms are close, their fluctuating dipole moments are
correlated, leading to attraction.

24. London Dispersion Forces
• These forces are
present in all
molecules, whether
they are polar or
nonpolar.
• The tendency of an
electron cloud to
distort in this way is
called polarizability.

25. Factors Affecting London Forces
• The strength of
dispersion forces tends
to increase with
increased molecular
weight.
• Larger atoms have
larger electron clouds
that are easier to
polarize.

26. Syllabus
• Go over syllabus with your “Team”
– Introduce yourselves
– Take a few minutes to read the syllabus
– Then, with your team, come up with at
least 3 questions you have about the
class that are NOT answered on the
syllabus
– Write the questions down on a 4 x 6
card (one card per team)
– I will collect the cards when you are
done and put together a handout
answering the questions.