Physical methods / analytical techniques

22 Jun 2018
Evaluation Methods: 

Discuss students responses with respect to the answer key.

Evaluation Results: 

This activty was developed for the IONiC VIPEr summer 2018 workshop, and has not yet been implemented.

Description: 

Inorganic chemists often use IR spectroscopy to evaluate bond order of ligands, and as a means of determining the electronic properties of metal fragments.  Students can often be confused over what shifts in IR frequencies imply, and how to properly evaluate the information that IR spectroscopy provides in compound characterization.  In this class activity, students are initially introduced to IR stretches using simple spring-mass systems. They are then asked to translate these visible models to molecular systems (NO in particular), and predict and calculate how these stretches change with mass (isotope effects, 14N vs 15N).  Students are then asked to identify the IR stretch of a related molecule, N2O, and predict whether the stretch provided is the new N≡N triple bond or a highly shifted N-O single bond stretch.  Students are lastly asked to generalize how stretching frequencies and bond orders are related based on their results.

 
Learning Goals: 
  1. Evaluate the effect of changes in mass on a harmonic oscillator by assembling and observing a simple spring-mass system (Q1 and 2)

  2. Apply these mass-frequency observations to NO and predict IR isotopic shift (14N vs. 15N) (Q3 and 4)

  3. Predict the identity of the diagnostic IR stretches in small inorganic molecules. (Q5, 6, and 7)

Equipment needs: 

Springs, rings, stands, and masses (100 and 200 gram weights for example).

 

Corequisites: 
Implementation Notes: 

Assemble students into small groups discussions to answer the questions to the activity and collaborate.

 

 

Time Required: 
Approximately 50 minutes
1 Jun 2018
Evaluation Methods: 

This LO has not been implemented; however, we recommend a few options for evaluating student learning:

  • implement as in-class group work, collect and grade all questions

  • have students complete the literature discussion questions before lecture, then ask them to modify their answers in another pen color as the in-class discussion goes through each questions

  • hold a discussion lecture for the literature questions; then for the following lecture period begin class with a quiz that uses a slightly modified problem.

Evaluation Results: 

This LO has not been implemented yet.

Description: 

In honor of Professor Richard Andersen’s 75th birthday, a small group of IONiC leaders submitted a paper to a special issue of Dalton Transactions about Andersen’s love of teaching with the chemical literature. To accompany the paper, this literature discussion learning object, based on one of Andersen’s recent publications in Dalton, was created. The paper examines an ytterbium-catalyzed isomerization reaction. It uses experimental and computational evidence to support a proton-transfer to a cyclopentadienyl ring mechanism versus an electron-transfer mechanism, which might have seemed more likely.

 

The paper is quite complex, but this learning object focuses on simpler ideas like electron counting and reaction coordinate diagrams. To aid beginning students, we have found it helpful to highlight the parts of the paper that relate to the reading questions. For copyright reasons, we cannot provide the highlighted paper here, but we have included instructions on which sections to highlight if you wish to do that.

 

Corequisites: 
Course Level: 
Learning Goals: 

After completing this literature discussion, students should be able to

  • Count the valence electrons in a lanthanide complex

  • Explain the difference between a stoichiometric and catalytic reaction

  • Predict common alkaline earth and lanthanide oxidation states based on ground state electron configurations  

  • Describe how negative evidence can be used to support or contradict a hypothesis   

  • Describe the energy changes involved in making and breaking bonds

  • On a reaction coordinate diagram, explain the difference between an intermediate and a transition state

  • Explain how calculated reaction coordinate energy diagrams can be used to make mechanistic arguments

Implementation Notes: 

This is a paper that is rich in detail and material. As such, an undergraduate might find it intimidating to pick up and read. We have provided a suggested reading guide that presents certain sections of the paper for the students to read. We suggest the instructor highlight the following sections before providing the paper to the students. While students are certainly encouraged to read the entire paper, this LO will focus on the highlighted sections.  

 

Introduction

            Paragraph 1

            Paragraph 2

            Paragraph 3

            Paragraph 4

First 5 lines ending at the word high (you may encourage students to look up exergonic if that is not a term commonly used in your department)

Line 14 starting with “In that sense,” through the end of the paragraph

            Paragraph 6

From the start through the word “endoergic” in line 22

Line 31 from “oxidation of” to the word “described” in line 33

Line 40 from “These” to the word “dimethylacetylene” in line 45

Paragraph 7

            From the start to the word “appears” in line 4

            The words “to involve” in line 4

            Starting in line 4 with “a Cp*” to “transfer” in line 5

Results and Discussion

            Paragraph 1

            Paragraph 2

            Paragraph 3 from the start through “six hours” in line 10

            Paragraph 4

            Paragraph 5

                        From the start to “solution” in line 3

                        From “This exchange” in line 10 to “allene” in line 11

                        From “Hence” in line 19 through the end of the paragraph

            Paragraph 6 from the start through “infrared spectra” in line 19

            Paragraph 7 from “Hence” in line 4 through the end of the paragraph

Mechanistic aspects for the catalytic isomerisation reaction of buta-1,2-diene to but-2-yne using (Me5C5)2Yb p 2579.

            Paragraph 1

            Paragraph 2

            Paragraph 3

            Paragraph 4

Experimental Section

            Synthesis of (Me5C5)2Yb(η2-MeC≡CMe).

            Synthesis of (Me5C5)2Ca(η2-MeC≡CMe).

Reaction of (Me5C5)2Yb with buta-1,2-diene

 

 

 

Time Required: 
One class period.
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
Corequisites: 
Equipment needs: 

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

Prerequisites: 
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
Course Level: 
Corequisites: 
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: 
Prerequisites: 
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.

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: 
Course Level: 
Corequisites: 
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.

 

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