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.

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

This question set has students examine the kinetics of the electrocatalytic reduction of CO₂ to CO described in Sampson, D.L.; Nguygen, D., Grice, K.A.; Moore, C.E.; Rheingold, A.L.; Kubiak, C.P. Manganese Catalysts with Bulky Bipyridine Ligands for the Electrocatalytic Reduction of Carbon Dioxide:  Eliminating Dimerization and Altering Catalysis.  J. Am. Chem. Soc. 2014, 136, 5460-5471. 

I do this activity as an introduction to the nature of science.  An object (not easily guessable) is put into a paper bag.  The job of the class is to figure out what is in the bag. At first, the students are simply shown the bag (sense of sight). Discussion (hypotheses) ensues on what could be in the bag.  I then walk around and shake the bag so students can hear what's in it (hearing). This results in more discussion, with some previous ideas being discarded. The bag is then passed around and students can feel (but not open!) the bag and also try to smell it.