Chem 433 9 15 11
This presentation is the property of its rightful owner.
Sponsored Links
1 / 10

CHEM 433 - 9/15/11 PowerPoint PPT Presentation


  • 81 Views
  • Uploaded on
  • Presentation posted in: General

CHEM 433 - 9/15/11. I. Introductory Topics C. Intermolecular Forces (handout, 18.1.-18.5) Conceptual overview cont. —> Recognizing IMF Quantitative Considerations - Energy Scales - Functional forms -Structural Considerations - Adding the repulsive Part

Download Presentation

CHEM 433 - 9/15/11

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Chem 433 9 15 11

CHEM 433 - 9/15/11

I. Introductory Topics

C. Intermolecular Forces (handout, 18.1.-18.5)

Conceptual overview cont.

—> Recognizing IMF

Quantitative Considerations

- Energy Scales

- Functional forms

-Structural Considerations

- Adding the repulsive Part

Read: Start Chapter 1 of Atkins

HW #2 via e-mail.. Today or tomorrow AM


Chem 433 9 15 11

Three key questions for identifying IMF?

1) Are ions present?

2) Are polar molecules present?

3) Are there molecules with OH, NH, or FH bonds?

Identify i) all and ii) the most significant IMF in the following liquids or mixtures?

CH3OH (l), C6H6 (l), O2(aq), KBr(aq), Kr(l)

D-ID*

DISP

D-D

H-B

Ion-D*

DISP

D-D

H-B

DISP*

DISP

D-D

H-B*

DISP*


Chem 433 9 15 11

CO2

CCl4


Chem 433 9 15 11

Structural Considerations: Bond Radii

http://en.wikipedia.org/wiki/Covalent_radius

http://en.wikipedia.org/wiki/Van_der_Waals_radius

http://periodictable.com/Properties/A/VanDerWaalsRadius.v.html

Rvdw (Ar) =


Chem 433 9 15 11

A 2-minute H-Bonding Case Study: “HF Dimer”or (HF)2

R(HF) = 0.919 Å

• E(H-Bond) = 3.6 kcal/mol

(15.1 kJ/mol)

• R(H…F) = 1.834 Å

(non bond R is ~ 2.7 Å !!!)

• Donor Bond lengthens:

R(HF, “A”) = 0.924 Å

• Charge rearrangement:

- more polarity

- partial e- transfer (0.05 e-)

B

A

Data are from a quantum chemical computation… (MP4/aug-cc-pVTZ)


  • Login