The colors of transition metal compounds are highly variable. Aqueous solutions of nickel are green, of copper are blue, and of vanadium can range from yellow to blue to green to violet. What is the origin of these colors? A simple geometrical model known as crystal field theory can be used to differentiate the 5 d orbitals in energy. When an electron in a low-lying orbital interacts with visible light, the electron can be promoted to a higher-lying orbital with the absorption of a photon. Our brains perceive this as color.

This is a truly hands-on activity in which students manipulate paper cutouts of carbon atomic orbitals and oxygen group orbitals to identify combinations with identical symmetry and build the carbon dioxide molecular orbital diagram. The activity pairs well with the treatment of MO theory in Miessler, Fischer, and Tarr, Chapter 5. An optional computational modeling component can be added at the end.

In this activity, a pair of students are show an object or molecule and are asked to determine the point group before their competitor.

A set of questions to be used in General or Introductory Inorganic Chemistry as a review or “quiz” of shapes and polarities.

In this activity, students in my upper-level Inorganic course are given two possible structures of sulfur dioxide, and based on an assessment of given vibrational modes, they determine which of the modes are IR active by two methods: (1) the “Intro Chem” method (determing whether the dipole moment changes for a particular vibrational mode) and (2) using character tables. They compare their assessment to experimental IR absorption peaks, and the students decide which structure is valid. For those of you who teach Raman spectroscopy, it could be included in this LO as well. 

In this activity, students will use gummies and toothpicks to construct models of molecules that will then be analyzed for their symmetry elements, and ultimately placed into the correct point group and the models can then be consumed.