This is an in-class assignment designed to help students integrate their understanding of periodic trends and materials properties. Using the color of alum crystals as an example of octahedral coordination chemistry, students use their knowledge of electronic structure and periodic trends to predict which of the isomorphous alum crystals will be colored, and to qualtitatively rank the degree of crystal field splitting in a family of alum crystals.
|The Structure and Color of Alums_student version.docx||383.19 KB|
|The Structure and Color of Alums_student version.pdf||181.58 KB|
In answering these questions, a student will:
- Apply knowledge of electron configurations to predict which metal ions will produce color.
- Use the spectrochemical series to determine whether the metal ions in an alum crystal will be high or low spin
- Compare field splitting for different alum compositions based on periodic trends
This worksheet was developed for a second-year descriptive inorganic chemistry class. Students have been introduced to periodic trends, electron configurations for transition metals, crystal structure and site symmetry, and are beginning a discussion of crystal field theory. They should also have been exposed to the spectrochemical series and ligand field splitting. This worksheet is used as a way of integrating knowledge across several chapters and several weeks of the semester, in preparation for a more advanced discussion of color in pigments and gemstones. After a brief introduction, students will work in small groups during class time to answer the worksheet questions. The questions follow closely with content in the textbook (Descriptive Inorganic Chemistry Raynor-Canham, Overton 6th ed.), and so should be mostly a review and opportunity for students to apply their understanding to a concrete problem.