Periodic trends

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

VSEPR: Flash Review

Submitted by Christopher Durr, Amherst College

This presentation is meant to be a review of applying VSEPRup to steric number 6. It's designed to be viewed as a powerpoint and printed out to keep for the student's notebook.

It can be used at multiple levels: as a review immediately after learning VSEPR in general chemistry, or as a refresher before starting upper level inorganic chemistry. The instructor could add text or voice over the slides to add more detail or leave the presentation as is for students.

If you'd like .psd or .pdf files of the drawings in these presentation, please contact me directly.

Learning Goals: 

After reviewing this material students should be able to:

Draw the correct VSEPR predicted structure of a molecule based on steric number and lone pair count.

Name VSEPR structures with their appropriate geometry.

Avoid common VSEPR mistakes, particularly those with steric number 5 and 6.

Recognize how lone pairs distort bond angles from ideal geometry in molecules like ClF3


Implementation Notes: 

I plan on uploading this flash review (along with others) to my class site before students arrive to my upper level inorganic course. I will voice over the slides, explaining the concepts, so they're ready to apply molecular orbital theory on the first day of class.

Time Required: 
10 - 15 Minutes
Evaluation Methods: 

I will compare student preparedness between this class and a previous one that did not receive a review.

Evaluation Results: 

This will be updated in the future.

5 Jun 2019

Zinc-Zinc Bonds (Expanded and Updated)

Submitted by Wesley S. Farrell, United States Naval Academy
Evaluation Methods: 

Performance and participation in the discussion will be assessed 

Evaluation Results: 

None collected yet. Evaluation data will be added in the future.


This paper in Science reports the synthesis of decamethyldizincocene, a stable compound of Zn(I) with a zinc-zinc bond. In the original LO, the title compound and the starting material, bis(pentamethylcyclopentadienyl)zinc, offer a nice link to metallocene chemistry, electron counting, and different modes of binding of cyclopentadienyl rings as well as more advanced discussions of MO diagrams. More fundamental discussion could focus on the question of what constitutes the evidence for a chemical bond, in this case, the existence of a zinc-zinc bond. In this updated LO, these topics are still covered, however additional topics, such as point group idenitifaction, details regarding the reaction mechanism, electronic structure, and  searching the literature using SciFinder are covered.  Additionally, electron counting is divided into both the covalent and ionic models.

Course Level: 
Learning Goals: 
  1. Students should become more confident reading the primary literature

  2. Students should be able to apply existing knowledge to interpret research results.

  3. Students should be able to apply electron counting formalisms to organometallic compounds.

  4. Students should be able to use 1H NMR spectroscopy data to rationalize structure.

  5. Students can rationalize bond distances based on periodic trends in atomic radii

  6. Students use SciFinder to put this work into a larger context.

  7. Students identify redox reactions based on oxidation changes.

  8. Students identify molecular point groups based upon structures.

  9. Students should be able to connect d electron count to observed colors of compounds. 

Related activities: 
Implementation Notes: 

Students are asked to read the paper and the accompanying Perspectives article before class as well as answer the discussion questions. The questions serve as a useful starting point for class discussion. 

Time Required: 
50 minutes


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