Physical methods / analytical techniques

10 Sep 2017

Inclusive Pedagogy: A Misidentified Molecule and Paper Retraction

Submitted by Sibrina Nichelle Collins, Lawrence Technological University
Evaluation Methods: 

This LO has various options for evaluation. First, a rubric should be prepared based on criteria identified by the student teams for evaluating the team posters. The students will be evaluated based on their ideas and attention to detail for their individual  reponses to the discussion questions. In addition, a 7-question survey is included in the handout for the students. Four of the questions address self-efficacy questions for chemistry majors. These questions were modified from a self-efficacy instrument developed by Baldwin et al for biology students. I have included a link to the model. We should be developing assessment tools that address science identity, sense of belonging, and self-efficacy for chemistry majors. If a student does not feel comfortable in a chemistry course, they will likely not pursue a career as a chemist.

Evaluation Results: 

Will be reported later.

Description: 

This learning object focuses on teaching students how to read and use Chemical and Engineering News for class discussions and critically evaluate the scientific literature. Recently, Chemical and Engineering News published an article about the retraction of a 15-year old paper, which had misidentified a multidentate ligand, which is central to the paper (Ritter, S.K. “Chemist Retract 15-year old paper and publish a revised version.” Chem. Eng. News, 2017, 95, (36), p6). The authors published a revised paper to the journal in 2017, with the correct structure of the ligand along with an x-ray crystal structure. This activity consists of two components, namely the students working in teams to discuss the C &E News article, retracted Inorganic Chemistry paper (DOI:10.1021/acs.inorgchem.7b01932) and the revised paper (DOI:10.1021/acs.inorgchem.7b01117) and preparing a poster for a “Gallery Walk.”

Learning Goals: 

An important learning goal for this learning object is to incorporate practices for creating an inclusive learning environment for students (inclusive pedagogy). The goals for this LO are for students to:

  • Read and use C&E News for student-led discussions
  • Critically evaluate experimental evidence published in the scientific literature
  • Apply concepts learned in previous chemistry courses
  • Gain a better understanding of the peer-review process for publication and retraction
  • Appreciate the importance of structural analysis tools such as X-ray crystallography
  • Prepare a team poster to communicate scientific ideas
Prerequisites: 
Equipment needs: 

The students will need 3M Post-IT paper and markers to prepare a poster for the "Gallery Walk."

Corequisites: 
Course Level: 
Implementation Notes: 

You will need to provide access to the Chemical and Engineering News article, and the two Inorganic Chemistry articles before class. This activity will likely take two class periods The first class period should focus on discussion of the articles and developing a rubric for evaluating the posters with the class. The second class period, the students will be allowed 30 min to prepare a poster for a "Gallery Walk."

Time Required: 
Two 50 min class periods
3 Jun 2017
Evaluation Methods: 

Students were evaluated by the instructor during the activity. The instructor was available throughout the activity to answer questions and guide inquiry. This activity generated good discussion among students and most were able to work their way through. 

Evaluation Results: 

All students completed the activity during the class period and gained a deeper appreciation for metals in biology, protein structure, and using NMR to determine protein structure. Some students needed more guiding through the rationales of metal toxicities and the multi-dimensional NMR experiments than others. 

Description: 

This activity was designed as an in-class group activity, in which students begin by using basic principles to predict relative toxicities and roles of metals in biological systems. Students then learn about the structures of metallothioneins using information from the protein data bank (PDB) and 113Cd NMR data. By the end of the activity, students will have analyzed data to identify and determine bonding models and coordination sites for multiple cadmium centers in metallothioneins. It is based on recent literature, but does not require students to have read the papers before class.

Learning Goals: 

Students will be able to:

  1. Use fundamental principles to predict toxicities of metals
  2. Apply hard-soft acid-base (HSAB) theory to metals in biological systems
  3. Utilize the protein data bank (PDB) to investigate protein-metal interactions
  4. Explain the roles of metallothioneins in biological systems
  5. Evaluate 1-D and 2-D 113Cd NMR to determine structures of Cd bonding sites in metallothioneins
  6. Explain how NMR can be utilized to determine protein structure
Corequisites: 
Course Level: 
Implementation Notes: 

This activity was developed for a Master's level bioinorganic course, but could be utilized in an advanced undergraduate inorganic course. Students were given the worksheet at the beginning of class and worked together in groups to answer the questions. Students did not have access to the paper and had not read any articles previously. Using the PDB was done as a separate in-class activity, so students had some familiarity with the PDB codes and amino acid sequences. 

A brief refresher of [1H-1H] COSY was presented before beginning the activity. 

Time Required: 
60 min
3 Jun 2017

Literature Discussion of "A stable compound of helium and sodium at high pressure"

Submitted by Katherine Nicole Crowder, University of Mary Washington
Evaluation Methods: 

Students could be evaluated based on their participation in the in-class discussion or on their submitted written answers to assigned questions.

Evaluation Results: 

This LO has not been used in a class at this point. Evaluation results will be uploaded as it is used (by Spring 2018 at the latest).

Description: 

This paper describes the synthesis of a stable compound of sodium and helium at very high pressures. The paper uses computational methods to predict likely compounds with helium, then describe a synthetic protocol to make the thermodynamically favored Na2He compound. The compound has a fluorite structure and is an electride with the delocalization of 2e- into the structure.

This paper would be appropriate after discussion of solid state structures and band theory.

The questions are divided into categories and have a wide range of levels.

Dong, X.; Oganov, A. R.; Goncharov, A. F.; Stavrou, E.; Lobanov, S.; Saleh, G.; Qian, G.-R.; Zhu, Q.; Gatti, C.; Deringer, V. L.; et al. A stable compound of helium and sodium at high pressure. Nature Chemistry 2017, 9 (5), 440–445 DOI: 10.1038/nchem.2716.

Corequisites: 
Learning Goals: 

After reading and discussing this paper, students will be able to

  • Describe the solid state structure of a novel compound using their knowledge of unit cells and ionic crystals
  • Apply band theory to a specific material
  • Describe how XRD is used to determine solid state structure
  • Describe the bonding in an electride structure
  • Apply periodic trends to compare/explain reactivity
Implementation Notes: 

The questions are divided into categories (comprehensive questions, atomic and molecular properties, solid state structure, electronic structure and other topics) that may or may not be appropriate for your class. To cover all of the questions, you will probably need at least two class periods. Adapt the assignment as you see fit.

CrystalMaker software can be used to visualize the compound. ICE model kits can also be used to build the compound using the template for a Heusler alloy.

Time Required: 
2 class periods
3 Jun 2017

An ion exchange method to produce metastable wurtzite metal sulfide nanocrystals

Submitted by Janet Schrenk, University of Massachusetts Lowell
Evaluation Methods: 

Evaluation methods are at the discretion of the instructor. For example, you may ask students to provide written answers to the questions, evaluate whether they participated in class discussion, or ask students to present their answers to specific questions to the class.

Description: 

In this literature discussion, students use a paper from the literature to explore the synthesis, structure, characterization (powder XRD, EDS and TEM) and energetics associated with the production of a metastable wurtzite CoS phase. Students also are asked define key terms and acronyms used in the paper; identify the goal of the experiments and determine if the authors met their goal. They examine the fundamental concepts around the key crystal structures available.  

 

Preserving Both Anion and Cation Sublattice Features during a Nanocrystal Cation-Exchange Reaction: Synthesis of a Metastable Wurtzite-Type CoS and MnS

Powell, A.E., Hodges J.M., Schaak, R.E. J. Am. Chem. Soc. 2016, 138, 471-474.

http://pubs.acs.org/doi/abs/10.1021/jacs.5b10624

 

There is an in class activitiy specifically written for this paper. 

Corequisites: 
Learning Goals: 

In answering these questions, a student will be able to…

  • define important scientific terms and acronyms associated with the paper;

  • describe the rocksalt, NiAs, wurtzite, and zinc blende in terms of anion packing and cation coordination;

  • differentiate between the structure types described in the paper;

  • explain the difference between thermodynamically stable and metastable phases and relate it to a free energy diagram; and

  • describe the structural and composition information obtained from EDS, powder XRD, and TEM experiments.

Prerequisites: 
Implementation Notes: 

This learning object was created at the 2017 IONiC Workshop on VIPEr and Literature Discussion. It has not yet been used in class.

Time Required: 
50 minutes
3 Jun 2017

Quantum Dot Growth Mechanisms

Submitted by Chi Nguyen, United States Military Academy
Evaluation Methods: 

The question document attempted by students in preparation for the literature discussion will be due prior to the in-class discussion. In particular, students' performance on the particle-in-a-box question will be evaluated to assess retention from the previously covered course material. The next exam following the discussion will contain specific question(s) (data/figure analysis) addressing these topics. Students' performance difference between the two will be evaluated. The extent to which students improve their post-discussion understanding of the concepts will direct future implementation.

Evaluation Results: 

To be determined. This is a newly proposed literature discussion.

Description: 

This literature article covers a range of topics introduced in a sophomore level course (confinement/particle-in-a-box, spectroscopy, kinetics, mechanism) and would serve as a an end-of-course integrated activity, or as a review activity in an upper level course. The authors of the article employ UV-vis absorption spectroscopy of CdSe quantum dots as a tool to probe the growth mechanism of the nanoparticles, contrasting two pathways.

 

Reference:  DOI 10.1021/ja3079576 J. Am. Chem. Soc. 2012, 134, 17298-17305

 
Corequisites: 
Prerequisites: 
Learning Goals: 

Apply the particle in a box model to interpret absorbance spectra with respect to nanoparticle size.

 

Analyze the step-growth and living chain-growth mechanisms proposed in this paper.

 

Evaluate the kinetics as it applies to the step-addition.

 

Recognize and apply multiple scientific concepts in an integrative manner.
Implementation Notes: 

Sophomore level implementation:  Recommend focusing on select portions (e.g. Figures 1b, 2, 5 with corresponding text) of the paper rather than having students read the entire document.  The learning objects focus on select topics, such as particle-in-a-box, reaction mechanism, and kinetics in conjunction with absorbance spectroscopy.  This would be a good literature discussion resource for an end-of-course integrative experience that encompasses multiple topics from general chemistry and inorganic chemistry.  

 

Advance level implementation:  For an upper division course, incorporate the paper in its entirety early in the course as an assessment on students’ ability to integrate multiple concepts that they should have learned in general chemistry, organic chemistry, and physical chemistry.  To enhance the experience, accompanying the literature discussion on this paper with a laboratory experience by repeating the experimental and characterization procedures presented in the paper, and having students' compare their results with published results.  This also serves to enhance students’ scientific literacy by critically assessing the quality of the paper.

 

Excerpts of the paper and questions can be used on a graded event, or as lesson preparation for in class discussion.

 
Time Required: 
In-class discussion takes approximately 50 minutes with students having already read the paper and submitted their responses to the questions.
3 Jun 2017
Evaluation Methods: 

This was created during the IONiC VIPEr workshop 2017 and has not yet been implemented.

 
Description: 

This module offers students an introductory chemistry or foundational inorganic course exposure to recent literature work. Students will apply their knowledge of VSEPR and basic bonding to predict geometries of complex SiO2-containing structures. Students will gain a basic understanding of how crystallography is used to determine molecular structures and compare experimental crystallographic data to their predictions.

Prerequisites: 
Corequisites: 
Course Level: 
Learning Goals: 

Students will be able to:

  1. Describe the bonding in SiO2 and related compounds
  2. Apply bonding models to compare and contrast bond types
  3. Apply VSEPR to predict bond angles
  4. Utilize crystallographic data to evaluate structures
Implementation Notes: 

Students should have access to the paper and read the first and fourth paragraphs on the first page and the third paragraph on the second page. Students should also reference scheme 1 and figure 1.

 

This module could be either used as a homework assignment or in-class activity.

 
5 May 2017

SOP4CV - A Web Resource for Cyclic Voltammetry Information

Submitted by Gerard Rowe, University of South Carolina Aiken
Description: 

http://sop4cv.com/

This is a great website created by Dr. Daniel Graham (who has the distinction of publishing a paper featured on TOC ROFL) to give anyone a working understanding of cyclic voltammetry techniques, their physical background, and the interpretation of their results.  

Prerequisites: 
Corequisites: 
Subdiscipline: 
Learning Goals: 

Students will gain experience interpreting the basic features of cyclic voltammograms, including: half-potential, electrochemical reversibility, chemical reversibility, and scan rate dependence

Students will learn the physical origins of the "duck" shape of a reversible CV using the Nernst equation and diffusion concepts

Students will learn what analytical methods are available using CV

Implementation Notes: 

None yet.  I'm considering creating an activity using the information in this website, but for now I just wanted to share this resource.

27 Mar 2017

Nanomaterials for Carbon Dioxide Reduction

Submitted by Anne Bentley, Lewis & Clark College
Evaluation Methods: 

The problems presented here represented half the points on the final exam – I have included point totals to give an idea of the weight assigned to each problem.

Evaluation Results: 

Twelve students were enrolled in my course in the fall 2016. The average overall score for these problems was 78%.

For problem 1b, I calculated the oxidation numbers using the familiar general chemistry method of assigning oxygen as –2 and hydrogen as +1. Students recently coming through organic may have some other way to do it, and you may need to provide directions for your students about your preferred method.  I think I could have worded part (c) better to try to emphasize the redox processes involved. I wanted them to think of combustion, but I think they needed to be specifically prompted, such as "Give an example of the combustion processes that generate CO2 and trace the oxidation state of carbon through the reaction." Overall my students scored 86% on problem 1.

The second problem (about another method that could be used to measure d-spacing) was fairly hit or miss.  Five students got full credit, six students got 3 points, and one got zero. Eleven out of twelve did answer part (a) correctly.  I realized as I made this LO that the article says the carbon-based material doesn’t diffract X-rays, but doesn’t actually directly explain whether or not the Cu nanoparticles diffracted X-rays, so you may need to adjust the question to be technically accurate.

Question three (re: surfactants in nanoparticle synthesis) referred back to knowledge from earlier in the course. The overall score was 61%.

Question 4 (define and describe electrodes) was fairly straightforward, and students scored 85%.

Question 5 caused some confusion, as some students missed that I was looking for “carbon-containing” products only. I didn’t count off for that mistake, but it made the problem harder for students who included hydrogen in each box.  Overall, students did very well on this problem (89% correct).

Question 6 – again, not too much trouble here (84% correct).

Question 7 – I was surprised that students didn’t do better on this question, as I thought that water reduction was mentioned often in the article.  Only three (of 12) students scored 5 points on this problem, and the average score was 53%.  This was probably my favorite question, as it foreshadows electrochemistry topics I cover in my inorganic course.

Description: 

This literature discussion is based on an article describing the use of copper nanoparticles on an N-doped textured graphene material to carry out the highly selective reduction of CO2 to ethanol (Yang Song et al., “High-Selectivity Electrochemical Conversion of CO2 to Ethanol using a Copper Nanoparticle / N-Doped Graphene Electrode” ChemistrySelect 2016, 1, 6055-6061.  DOI: 10.1002/slct.201601169). The article provides a good introduction to the concepts of electrochemical reduction, selectivity and recycling of fossil fuels. The literature discussion assignment shared here was used as half of the final exam in a half-credit nanomaterials chemistry course, but could be adapted for use as a take-home or in-class assignment.

Corequisites: 
Course Level: 
Learning Goals: 

After reading this paper and working through the problems, a student will be able to:

  • assign oxidation states to carbon and trace the oxidation and reduction of carbon through fossil fuel combustion and CO2 conversion
  • describe the role of control experiments in studying the CO2 conversion presented in the article
  • define the word “selective” in the context of this research
  • use the proposed mechanism to explain why the electrode studied produces ethanol in such a high proportion
  • identify the primary reaction competing with CO2 reduction for available electrons
Implementation Notes: 

These questions comprised half of the final exam for my half-credit nanomaterials chemistry course in the fall of 2016.  I gave the article to the students one week ahead of time. They were encouraged to read the article, make any small notes they liked, and meet with me in office hours with questions. At the final exam they were allowed to use their copy of the article, but they were also required to hand in their copy with their exam so that I could make sure they hadn't written lots of extraneous information on the exam copy.

The nanomaterials course features near-weekly homework assignments centered around articles from the literature. Because I used this article at the end of the course, students were already familiar with nanomaterials synthesis and characterization techniques. Thus, some of the questions I asked relied on previous knowledge. 

Please feel free to adapt these questions and add some of your own. Leave comments describing any new questions you’ve added.

Time Required: 
one hour

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