Physical methods / analytical techniques

9 Jun 2019

Chem 165 2018

Submitted by Adam R. Johnson, Harvey Mudd College

This is a collection of LOs that I used to teach a junior-senior seminar course on organometallics during Fall 2018 at Harvey Mudd College. There were a total of 9 students in the course. The Junior student (there was only one this year) was taking 2nd semester organic concurrently and had not takein inorganic (as is typical).

Subdiscipline: 
Corequisites: 
Course Level: 
8 Jun 2019

VIPEr Fellows 2019 Workshop Favorites

Submitted by Barbara Reisner, James Madison University

During our first fellows workshop, the first cohort of VIPEr fellows pulled together learning objects that they've used and liked or want to try the next time they teach their inorganic courses.

6 Jun 2019
Evaluation Methods: 

The guided reading questions may be graded using the answer key. 

Evaluation Results: 

These questions have not yet been assigned to students.

Description: 

Guided reading and in-class discussion questions for "High-Spin Square-Planar Co(II) and Fe(II) Complexes and Reasons for Their Electronic Structure."

Course Level: 
Learning Goals: 

1.  Bring together ligand field theory and symmetry.

  1. Students should be able to identify symmetry of novel molecules in the literature.

  2. Students should be able to explain d-orbital ordering in a coordination complex using ligand field theory.

  3. Students should be able to identify donor/acceptor properties of previously unseen ligands.

  4. Students should be able to apply your knowledge of electronic transitions to the primary literature.

  5. Students should be able to become more familiar with 4-coordinate geometries.

  6. Students should be able to predict magnetic moments of high-spin and low-spin square-planar complexes.

  7. Students should be able to identify properties of ligands that favor formation of the highly unusual high-spin square planar complexes.

2.  Students should comfortable with reading and understanding primary literature.


 

Related activities: 
Implementation Notes: 

You do not have to assign all of the guided reading questions at once.  You may consider assigning questions as they pertain to where you are in your inorganic chemistry class.

Time Required: 
this has not been used yet for in-class discussion.
6 Jun 2019
Description: 

This Literature Discussion is based on the article “Square-planar Co(III) {O4} coordination: large ZFS and reactivity with ROS” by Linda Doerrer et. al.   It includes a reading guide that will direct students to specific sections of the paper that highlight some of the key results and analytical techniques that lead to them.

Corequisites: 
Course Level: 
Learning Goals: 
  1. Interpret results in high-level scientific papers, which will help them gain confidence in their abilities to read papers.

  2. Identify conclusions from the text of a paper, given an indicated scheme and data set.

  3. Synthesize multiple conclusions from different sections of a paper into an overall understanding of the conclusions of a paper

  4. Relate oxidation state to bond lengths in real examples

  5. Compare low- and high-spin d-orbital splitting diagrams.

  6. Identify unpaired electrons in a splitting diagram.

  7. Relate electron-density to acidity and ligand field strength.

  8. Recognize that science is collaborative and involves experts in many fields.

Implementation Notes: 

These questions are drawn from key conclusions in the text of the paper. It could be useful to highlight the specific areas of the text, or to include a statement like the following:

 

"For the following questions, specific figures and acronyms are mentioned. Often, authors will include a reference to a specific figure in the text when they are drawing conclusions from the data, and so it can be useful to find those specific sentences in the text of the paper when you are analyzing their data and conclusions."

31 May 2019

Helping Students with Visual Impairments See Colors

Submitted by Douglas Balmer, Warwick High School
Evaluation Methods: 

Do these students identify the same colors as the students without visual impairments?

Are their lab results correct? 

Evaluation Results: 

Students were able to accurately describe colors.

Description: 

I have had some students in class have a hard time identifying colors (flame tests, solution color, acid-base indicators, etc.) because of a visual impairment. There are many cell-phone apps that are helpful in aiding these students. "Pixel Picker" allows the students to load a picture from a device (cell phone, ipad). This is helpful because students are now dealing with a "frozen" image. Moving the cross-hair to different parts of the picture changes the R-G-B values. The "Color Blind Pal" app uses a more qualitative approach. It names the color in the cross-hair using various color scales. There are also different options for different types of color blindness. 

Both of these apps are free and availble in the App Store.

Prerequisites: 
Corequisites: 
Course Level: 
Learning Goals: 

A student should be able to correctly identify an unknown metal by the color of its flame.

A student should be able to correctly identify the endpoint in a titration by the indicator's color change.

A student should be able to correctly describe the physical properties (color) of a sample.

A student should be able to correctly predict the visible absorbance spectrum of a solution based on correctly identifying the color of the solution.

Implementation Notes: 

Have the students with visual impairments practice using the app ahead of time to better prepare them to use the app for the first time in class/lab. Students would also need to understand the additive nature of light colors. For example, high R and G values will appear yellow/orange. I would give these students a 1-page handout for their lab notebook with the addative color wheel and various colored circles labeled with their names and RGB values so that students could practice and reference in the lab.

Our lab safety contract actually has students indicate whether they are color blind. This is a good time to introduce these students to the apps.

Time Required: 
15 min
23 May 2019

CompChem 05: Infrared, Thermochemistry, UV-Vis, and NMR

Submitted by Joanne Stewart, Hope College
Evaluation Methods: 

This exercise takes longer than a 50 minute class period, so we get as far as we can in one class and the students complete the exercise as homework. Students write their answers to the questions directly on the handout. Tables are provided for recording numerical results, but because of some (simple) required mathematical manipulations, it is easier if students set up a spreadsheet and record their numerical results there. The handouts with their answers and printed copies of their spreadsheet are collected in the next class.

Evaluation Results: 

In Exercise 1, the vibrational spectrum of formaldehyde is calcuated by three different methods. Because the vibrational modes come out in a different order, energy-wise, in one of the methods, students have trouble keeping track of which vibration is which. Each mode is labeled with the correct symmetry label, which should help them. Plus, they can click on each mode and visualize it.

Exercise 2 involves calcuating delta H for an "isodesmic" reaction: one in which the total number and type of bonds is the same in reactants and products. This helps cancel any systematic errors in the calculations. If this is one of the first time that students have worked in "hartrees," it is helpful to explain that unit to them. Students compare semi-empirical calculations with HF and DFT, and in this example, the HF and DFT calculations give much more accurate results.

Exercise 3 is about calculating UV-Vis spectra, but more importantly it walks students through drawing more complicated molecules. The CIS/ZINDO approach is used for the UV-Vis calcuation, which may not be highly accurate, but is very fast, so students get rapid results that they can compare.

In Exercise 4, students calculate NMR spectra for three different molecules. It teaches students about chemical shifts, but it does not cover coupling constants. If students are experienced with NMR, the averaging of proton resonances (such as the three protons in a methyl group) has become second nature to them. This exercise forces them to think about how those resonances are averaged.

 

Description: 

This is the fifth in a series of exercises used to teach computational chemistry. It has been adapted, with permission, from a Shodor CCCE exercise (http://www.computationalscience.org/ccce). It uses the WebMO interface for drawing structures and visualizing results. WebMO is a free web-based interface to computational chemistry packages (www.webmo.net).

In this exercise, students perform infrared, thermochemistry, UV-Vis, and NMR calculations. They compare the results from different methods and basis sets to experimental values.

The exercise provides detailed instructions, but does assume that students are familiar with WebMO and can build molecules and set up calculations.

Learning Goals: 

Students will be able to:

  1. Calculate an IR spectrum. Visualize the normal modes. Use appropriate scale factors to “correct” the calculated values.
  2. Calculate NMR spectra and average the chemical shift values for the static structures (in 1H NMR) to approximate the experimental spectrum.
  3. Calculate UV-Vis spectra.
Equipment needs: 

Students need access to a computer, the internet, and WebMO (with Mopac and Gaussian). 

Course Level: 
Corequisites: 
Implementation Notes: 

I use this as an in-class exercise. Students bring their own laptops and access our institution's installation of WebMO through wifi.

Time Required: 
2 hours

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