Physical properties

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

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.
18 Jan 2017

calistry calculators

Submitted by Adam R. Johnson, Harvey Mudd College
Description: 

I just stumbled on this site while refreshing myself on the use of Slater's rules for calculating Zeff for electrons. There are a variety of calculators on there including some for visualizing lattice planes and diffraction, equilibrium, pH and pKa, equation balancing, Born-Landé, radioactive decay, wavelengths, electronegativities, Curie Law, solution preparation crystal field stabilization energy, and more.

I checked and it calculated Zeff correctly but I can't vouch for the accuracy of any of the other calculators. 

Prerequisites: 
Corequisites: 
Learning Goals: 

This is not a good teaching website but would be good for double checking math

 

Implementation Notes: 

I used this to double check my Slater's rules calculations (and found a mistake in my answer key!)

30 Jun 2016

Basics of Lanthanide-Based Photophysics

Submitted by Jacob Charles Lutter, University of Michigan
Description: 

This 5 slides about outlines the basics of lanthanide photophysics as a primer for those new to the topic.  These properties are very unique and actually very useful, which is a topic for another time.  The intricacies of what causes the Ln luminescence, its strengths and drawbacks are discussed along with how these drawbacks are addressed in molecular complexes.  Notes for the instructor are included that explain each slide.

Prerequisites: 
Course Level: 
Subdiscipline: 
Learning Goals: 

Students should be able to explain the Laporte selection rule, and why it is so important to the Ln photophysical properties of absorption/excitation and lifetimes.

Students should be able to explain how the intrinsic nature of the 4f orbitals creates advantages and disadvantages for luminesecence.

Students should be able to design possible antenna ligands based on desired characteristics.

Implementation Notes: 

Feel free to use all or part of this presentation as you see fit. 

27 Jun 2016

Online Homework for a Foundations of Inorganic Chemistry Course

Submitted by Sabrina G. Sobel, Hofstra University
Evaluation Methods: 

Students are graded on a sliding scale based on the number of attempts on each question. An overall grade is assigned at the end of the semester, adjusted to the number of points allotted for the homework in the syllabus. 

Evaluation Results: 

Student performance on the overall homework assignments for the semester includes questions assigned on General Chemistry topics that are part of this class syllabus. 

 201420152016
Number404741
Average89%80%83%
S.D.15%19%23%

In addition to gethering data on overall  performance, I and my student assistants, Loren Wolfin and Marissa Strumolo, have completed a statistical study to assess performance on individual questions, and to identify problem questions that need to be edited. We identified two separate issues: incorrect/poorly worded questions, and assignment of level of difficulty. Five problematic questions were identified and edited. The level of difficulty was reassigned for eight questions rated as medium (level 2); six were reassigned as difficult (level 3), and two were reassigned as easy (level 1). I look forward to assessing student performance in Spring 2017 in light of these improvements. Please feel free to implement this Sapling homework in your class, and help in the improvement/evolution of this database.

Description: 

The Committee on Professional Training (CPT) has restructured accreditation of Chemistry-related degrees, removing the old model of one year each of General, Analytical, Organic, and Physical Chemistry plus other relevant advanced classes as designed by the individual department. The new model (2008) requires one semester each in the five Foundation areas: Analytical, Inorganic, Organic, Biochemistry and Physical Chemistry, leaving General Chemistry as an option, with the development of advanced classes up to the individual departments. This has caused an upheaval in the treatment of Inorganic Chemistry, elevating it to be on equal footing with the other, more ‘traditional’ subdisciplines which has meant the decoupling of General Chemistry from introduction to Inorganic Chemistry. No commercial online homework system includes sets for either Foundations or Advanced Inorganic Chemistry topics. Sapling online homework (www.saplinglearning.com) has been open to professor authors of homework problems; they have a limited database of advanced inorganic chemistry problems produced by a generous and industrious faculty person. I have developed a homework set for a semester­-long freshman/sophomore level Inorganic Chemistry course aligned to the textbook Descriptive Inorganic Chemistry by Rayner-Canham and Overton (ISBN 1-4641-2560-0, www.whfreeman.com/descriptive6e ), and have test run it three times. Question development, analysis of student performance and troubleshooting in addition to topic choices, are critical to this process, especially in light of new information about what topics are taught in such a course (Great Expectations: Using an Analysis of Current Practices To Propose a Framework for the Undergraduate Inorganic Curriculum: http://pubs.acs.org/doi/full/10.1021/acs.inorgchem.5b01320 ).This is an ongoing process, and I am working to improve the database all the time.

Prerequisites: 
Corequisites: 
Course Level: 
Learning Goals: 

1.      Increase understanding in these topic areas:

a.      Acid-base chemistry and solvent systems

b.      Bonding models of inorganic molecules and complexes

c.      Bonding models in extended systems (solids)

d.      Descriptive chemistry and Periodic Trends

e.      Electronic structure of inorganic molecules, complexes and solids

f.       Extended structures: unit cells and other solid-state structural features

g.      Molecular structure and shape of inorganic molecules

h.      Inorganic Complexes nomenclature, bonding and shapes

i.       Redox chemistry and application to inorganic systems

j.       Thermodynamics as applied to inorganic solids and inorganic systems

2.      Practice using knowledge in these topic areas:

a.      Acid-base chemistry and solvent systems

b.      Bonding models of inorganic molecules and complexes

c.      Bonding models in extended systems (solids)

d.      Descriptive chemistry and Periodic Trends

e.      Electronic structure of inorganic molecules, complexes and solids

f.       Extended structures: unit cells and other solid-state structural features

g.      Molecular structure and shape of inorganic molecules

h.      Inorganic Complexes nomenclature, bonding and shapes

i.       Redox chemistry and application to inorganic systems

j.       Thermodynamics as applied to inorganic solids and inorganic systems

Implementation Notes: 

The database of homework questions is available through Sapling Learning. They can be implemented as an online homework set for a class. Students need to buy access to the Sapling online homework for the duration of the class, typically $45.

Time Required: 
variable
27 Jun 2016

Inquiry-Based Introduction to Carbonyl Ligands

Submitted by Emily Sylvester, Wheeling Jesuit University
Evaluation Methods: 

I will assess this activity with a problem set question and/or exam question. I generally ask students to explain/predict bonding or properties of a similar or isoelectronic ligand (CN-, N2, etc.).

Description: 

This in-class worksheet introduces students to the different ways we describe organometallic ligands – bonding, properties, spectroscopy, etc. – using carbon monoxide as an example. It is structured as an inquiry-based activity, where students work together in small groups but check in with the entire class at appropriate intervals. I plan to use this activity with my advanced inorganic students next year.

Learning Goals: 

Students will be able to:

  • Use the MO diagram, specifically frontier orbitals, of a ligand to predict the bonding (sigma, pi, donation, acceptance) interactions in an organometallic complex.
  • Describe and draw the molecular orbital interactions of a terminal CO ligand and a symmetric μ2-CO ligand with a metal.
  • Describe and explain the σ-donating and π-accepting nature of the CO ligand.
  • Understand and apply the terms backbonding and backdonation.
  • Articulate the relationship between the M-C and C-O bond strengths in a carbonyl complex.
  • Relate the CO stretching frequencies of two or more carbonyl complexes to the strength of the metal-ligand interaction and to the electron density on the metal fragment.
  • Describe various possible binding modes of a CO ligand.
Corequisites: 
Subdiscipline: 
Prerequisites: 
Course Level: 
Implementation Notes: 

I haven’t used this in class yet, but I plan to implement it in my advanced inorganic course. My class size ranges from 4-12 students. Students must have learned MO theory, and we will have already discussed electron counting. I anticipate that this worksheet will require one 50-minute class period. Though students will work on the activity on their own, we will convene as a class after each section to make sure all of the groups are on the right track. I anticipate that this activity will provide a solid framework for subsequent discussions of OM ligands (hydrides, dihydrogen, pi systems).

Time Required: 
I anticipate that this worksheet will require one 50-minute class period.
27 Jun 2016

Will it Float? Density of a Bowling Ball Activity

Submitted by Terrie Salupo-Bryant, Manchester University
Evaluation Methods: 

I collect the group activity sheets at the end of class and check if their procedure, calculations and conclusions are correct.

They have at least one or two exam questions on the chapter test that require them to apply density concepts and calculations. I haven't saved their responses in the past, but will do so when I use this activity in the future.

On the ACS General portion of the GOB standardized exam, they are required to calculate volume given the mass and density of a substance.

Evaluation Results: 

Usually when I check each group's original calculations during class, 3 to 4 groups out of nine will have made at least one calculation error (e.g. failure to convert from U.S. to metric units, incorrect calculation of radius). At the end of class usually 1 or 2 groups still have an error somewhere in their calculation. On occasion, one group may not make the correct relationship between their calculated density of the ball, the reported density of water, and whether the ball sinks or floats.

On the ACS standardized GOB exam, the number of students who were able to calculate volume given density and mass ranged from 67% to 75% over the past four years of teaching this introductory chemistry course.

Description: 

This activity was adapted from the J. Chem. Ed. article, “Discrepant Event: The Great Bowling Ball Float-Off.” In this activity students use a bowling ball and some basic materials to predict whether the ball will sink or float in a tub of liquid. 

Students in groups of 3 or 4 are assigned a bowling ball. For conventional bowling balls (circumference ranging from 26.704 inches to 27.002 inches[1]) those weighing less than 12 pounds will float and those weighing more than 12 pounds will sink. I have a variety of bowling balls (the bowling alleys I visited were more than happy to donate a ball to science), so the answer to the question, “Will it float?” depends on which ball they were assigned. They may only answer the question using available materials: bowling ball, string, ruler, graduated cylinder, calculator, textbook, balance, and a handout of geometric equations. They are also asked further questions that probe their understanding of density.                                                                                                       

[1] “USBC Equipment Specifications and Certifications Manual” updated April 2016, www.Bowl.com <accessed June 25, 2016>, p. 6.

Learning Goals: 

Students will be able to:

1.      Calculate density from mass and volume.

2.      Convert from standard U.S. units to metric units.

3.      Use density to predict whether an object will sink or float in water. 

Prerequisites: 
Corequisites: 
Topics Covered: 
Course Level: 
Equipment needs: 

One bowling ball for each group of 3-4 students, a balance that can measure in pounds, string, rulers, graduated cylinders, cork rings to hold bowling balls, large tub of water.

Subdiscipline: 
Implementation Notes: 

I don’t mention the word “density” in my introduction of the activity though they should have done the textbook reading on density prior to coming to class.  I offer a graduated cylinder to account for the holes, but in four years of doing this activity only one student has inquired about using one to make the volume correction. The results still come out fine if the volume correction is ignored. My 12 pound bowling ball eventually sinks though the average density that students calculate for this ball is slightly less than the density of the water.

You may want to pose the following questions to students:

Do the holes make a difference in your calculations?

Can you assume that the liquid in the tub is water?  Does it make a difference what the liquid is?

Will the density of the bowling ball change if you cut it in half?  Will it still float/sink?

 A common misconception is that whether it floats depends on mass alone. I demonstrate this is not the case by putting a marble in the tub with a bowling ball that floats. Considering mass alone does not account for the fact that the marble sinks and the ball floats.

 

Time Required: 
One 50 minute class period
10 Jun 2016

Chapter 1--Stanley Organometallics

Submitted by George G. Stanley, Louisiana State University
Description: 

chapter 1 of George Stanley's Organometallics course: Introduction, Orbitals, Electron counting

This chapter is an overview of the field, with an emphasis on electron counting

The powerpoint slides contain answers to some of the in-class exercises, so those are behind the "faculty only" wall. I shares these with students after the class, but not before.

everyone is more than welcome to edit the materials to suit their own uses, and I would appreciate being notified of any mistakes that are found.


Prerequisites: 
Course Level: 
Corequisites: 
Subdiscipline: 
Learning Goals: 

students will count electrons for various organometallic complexes

students will get a broad overview of organometallic chemistry

14 May 2016

soapmaking activity

Submitted by Adam R. Johnson, Harvey Mudd College
Evaluation Methods: 

the exercises were evaluated according to the keys provided

Description: 

This in-class activity is designed to follow the linked lecture/demonstration on soapmaking. The soaps cure enough to be handled in 48 hours if kept warm, and the students can feel the difference in the canola/coconut oil soaps.

The calcuations go through the major reactions, functional groups, and physical properties of soap molecules, and ends with the calculation of molecular weight for a mixture of substances. This could be related to a later polymer unit.

I include "Team Cards" so that some of the calculations are divided into a class dataset that could be presented in the last 5-10 minutes of class.

For 2016, I will have students do more of calculations, and then report back to the class on their results in a subsequent class period; there was not enough time for the reporting last year.

Learning Goals: 

1.    Identify the major functional groups found in soap and used in soapmaking
2.    Explain how soap works at the molecular level
3.    Draw balanced chemical reactions for the soapmaking process
4.    Calculate various metrics for soap and relate them to the soap’s properties
5.    Compare different ways of calculating the molecular weight of soap and polymers
 

Equipment needs: 

none

Corequisites: 
Prerequisites: 
Course Level: 
Related activities: 
Implementation Notes: 

the students struggled with the MW calculations and I would appreciate input on how to change this to help them understand it better.

Time Required: 
1 50 minute class period
14 May 2016

soapmaking lecture/demo

Submitted by Adam R. Johnson, Harvey Mudd College
Description: 

This is a short presentation that outlines the major chemical reactions of soapmaking. Included are instructions for making two soaps, one from canola oil, the other from coconut oil. These two soaps have very different hardnesses, which can be explained by examining the structures of the oils. If you have never made soap before, it isn't that difficult, but it does use concentrated NaOH so is very caustic before the reaction is done. The linked websited have good instructions for soapmaking as well.

The powerpoint is annotated with notes and suggestions. There is a student handout too.

Questions are provided that students could do as homework. The answers are included as faculty only files.

Prerequisites: 
Corequisites: 
Learning Goals: 

1.    Identify the major functional groups found in soap and used in soapmaking
2.    Explain how soap works at the molecular level
3.    Draw balanced chemical reactions for the soapmaking process
4.    Calculate various metrics for soap and relate them to the soap’s properties
5.    Compare different ways of calculating the molecular weight of soap and polymers
 

Course Level: 
Related activities: 
Implementation Notes: 

This was used as the first day in a two-day module in first-year chemistry. The second day used in-class small group work to calculate some of the metrics in soap and further examine the chemistry of soap. For 2016, I am adding a third day to finish up calculations and have groups report back on their findings.

Time Required: 
one class period (two if doing the followup activity)
Evaluation
Evaluation Methods: 

There was no evaluation on the lecture/demo. The exercises were graded according to the provided key. The answer key here is the same as the first answer key in the linked in-class activity.

Evaluation Results: 

Students were generally able to do the calculations without too much trouble, once they realized it was just a limiting reagent calculation. I got several actual "cartoons" for the 2nd part, and I awarded bonus points for students who were creative and drew me a 1 or 4 panel comic strip.

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