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.
This LO has not been implemented yet.
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.
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
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.
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
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
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 3 from the start through “six hours” in line 10
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.
Synthesis of (Me5C5)2Yb(η2-MeC≡CMe).
Synthesis of (Me5C5)2Ca(η2-MeC≡CMe).
Reaction of (Me5C5)2Yb with buta-1,2-diene
I do not do any formal assessment of student learning for this activity, but instead I judge understanding by the quality of the in-class dicussion.
I have also used similar questions on exams in the past to see if the students can apply these ideas to different reactions.
I have experienced mixed results with this exercise over the three years I have used it. I find that my students have no trouble identifying that a reaction has occurred and they readily recognize that the color change is a consqeuence of the reaction.
My students tend to struggle with the composition of the complex ions in solution. For the CrCl3 solution, students provide many possible compositions of the coordination complex including the neutral complex, [CrCl3(OH2)3], and the hexaaqua complex, [Cr(OH2)6]3+. More than 2/3 of the students suggest one of the two predominant complex ions that are present in solution. For the Cr(NO3)3 solution, students often want to use the nitrate as a ligand on the chromium center.
All of my students are usually able to write the balanced reactions and explain the changes in the UV-visible spectra once they identify the composition of the complex cations.
Students in inorganic chemistry courses are often interested in the colors of transition metal complexes. This in-class activity serves an introduction to reactions of coordination complexes and pushes students to think about the relationship between the color of a complex cation and its structure. Students are provided with pictures of aqueous solutions of two chromium(III) salts [CrCl3*6 H2O and Cr(NO3)3*9 H2O] at two different times and are then asked to explain the changes observed in the solutions. This activity was inspired by a laboratory experiment which was done as part of the inorganic laboratory course for many years ("Determination of Delta_oct in Cr(III) Complexes" from Szafran, Z., Pike, R.M., and Singh, M.M "Microscale Inorganic Chemistry: A Comprehensive Laboratory Experience" Wiley, New York, (c)1991) .
After completing this exercise, students should be able to:
- describe how the color of a solution is related to the composition of the coordination complex present in solution,
- explain how the change in color of a solution indicates that a reaction has occured, and
- determine the identities of the products and reactants of a reaction that has taken place in solution.
If the UV-visible data are also provided, students should also be able to relate the shifts in the peaks observed in the UV-visible spectra to the position of the ligands in the spectrochemical series.
No equipment is needed for this in-class activity.
I usually use this activity to introduce reactions of coordination complexes in lecture, which falls just after a section in my text on the colors of coordination complexes. While my students have seen many transformations in lab, I use this to connect the two portions of the course. For added empahsis you could make the aqueous solutions and bring them to class.
I usually project the pictures on a screen at the front of the class and I therefore need a device to project it from and a projector.
I break up my class into groups and let them work on this activity collaboratively. I usually let them discuss the problem for about 5-10 minutes and I check in with each group individually. If they are having trouble determining the composition of the coordination complexes, I remind them that they need to write out the formulas in the current way that we represent coordiantion complexes. This usually gets them thinking about primary vs. secondary coordination spheres and waters of hydration. I then let them work for another 10 minutes so that they can write the reactions. I then bring the class together to discuss the results. If time allows, I share the UV-visible data with the entire class and as them to explain the observed changes.
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.
Will be reported later.
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.”
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
The students will need 3M Post-IT paper and markers to prepare a poster for the "Gallery Walk."
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."