5 Jan 2015

The Color and Electronic Configurations of Prussian Blue

Literature Discussion

Submitted by Erica Gunn, Simmons College

I used this paper to illustrate several course concepts related to materials structure (crystal lattice structure, coordination number, crystal field theory and orbital splitting, symmetry, electronic spectra, allowed and forbidden transitions). This activity was paired with a laboratory experiment (see related VIPEr objects) in which students synthesized Prussian Blue, and gave students a really in-depth look at what was going on when they mixed those solutions together. Combined with another VIPEr activity that uses a more recent literature example (New Blue Solid, in related links), students gained a broad appreciation for how inorganic chemists can use these concepts to rationally design new materials.



Learning Goals: 

Become familiar with reading chemical literature

Use symmetry and electronic configuration to interpret absorption spectra

Integrate understanding of course concepts to understand a "real life" literature example and enhance student interest 

Implementation Notes: 

These activities were used in a 200-level course, which happened to mostly populated by juniors and seniors. The reading questions were designed mainly to check for basic comprehension. Most students had no difficulty answering the "what" questions about the experiments done and facts presented, but many needed significant guidance to understand why the researchers made these particular measurements, and how they interpreted the data to arrive at the conclusions presented. Most of the class discussion focused on building a "big picture" overview of what was going on. This led to interesting questions about design of experiments and use of evidence in science. Several students were surprised at how much of the scientific argument they had missed in their first reading of the paper, even though they felt like they had a good grasp on the data that the authors had reported.

Time Required: 
1 hour
Evaluation Methods: 

Student answers to the reading comprehension questions were collected at the beginning of class and graded out of 10 points (largely based on participation and completeness of answers). 

Evaluation Results: 

Most students were able to identify the correct answers from the paper, though some were confused by the last section involving orbital calculations (this was expected, as most of these students have not yet had a course in quantum mechanics). 

Some students also had difficulty following the logic presented in the paper to predict differences in absorption band intensity for the different Fe compounds. Most recognized that the absorption band position was important and some realized that intensity also mattered, but most did not fully follow the arguments for assigning absorption spectra to one particular complex geometry. Most of the class discussion involved recreating the logic behind the peak assignment for the absorption spectra.

Creative Commons License: 
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