The goal of this activity is to have students calculate the empirical formula of a compound given the contents of a unit cell.
A repeating building block, or unit cell, is used to represent extended structures since shifting a unit cell along its edges by the length of the edge will exactly replicate the extended structure.
This learning object is aimed at getting students to think critically about the data they collect in lab as they collect the data similar to how chemists typically conduct research. They will be given a pre-lab video and a procedure prior to lab, conduct the experiment, and then upload their data to an Excel spreadsheet. Students will then stay in their group to discuss the questions given to them on the worksheet in class with the instructor, and are allowed to continue working on them as a group up until the due date.
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.
The page has JSmol structures for unic cells including cubic, body centered cubic, and face centered cubic unit cells as well as for CsCl, Ni3Al, Cu2O, NaCl, CaF2, ZnS, diamond, Li3Bi, NaTl, NiAl and ReO3. The advanced page also has triclinic, monoclinic, hexagonal, orthorhombic, and tetragonal cells with all possible centering.
Although I’m a solid state chemist, I still find it difficult to teach the visualization of solid state structures. I’m interested in any tool that helps my students visualize solids. My experience is that the more representations students can master, the more likely they are to find one that helps them understand solid state structures.
I’ve used many tools. These include
We do not cover extended solids (solid state materials) in our general chemistry program. With the exception of students who have taken a course in materials science, Inorganic Chemistry I is the first time our students have encountered solid state structure. Although they have built some visualization skills by working with molecules and symmetry, they do not have robust 3D visualization abilities and have trouble using the language of solid state chemistry (unit cells, packing, filling holes, coordination number, etc…) in the context of structure.
This is a short worksheet that guides students through simple metal lattices (SCP, CCP, HCP) and how filling holes in these lattices results in ionic lattices (NaCl, CsCl, fluorite, etc.).
The worksheet was used as an in-class activity after students had read about the material in the text. This activity is probably suitable for first-year students, though I used it with juniors/seniors.
Equilibrium reactions are those that are dynamic: the reaction can shift to form more reactants or more products depending on the physical or chemical conditions present. They were discovered and described empirically, but have a thermodynamic basis in the Gibbs Energy of the reaction. A reaction at equilibrium has both reactants and products present, and the rate of formation of products is equal to the rate of formation of reactants. A common application of equilibrium is the chemistry of aqueous acids. Acid strength is measured by the pH scale.
Equilibrium reactions are those that are dynamic: the reaction can shift to form more reactants or more products depending on the physical or chemical conditions present. They were discovered and described empirically, but have a thermodynamic basis in the Gibbs Energy of the reaction. A reaction at equilibrium has both reactants and products present, and the rate of formation of products is equal to the rate of formation of reactants. A common application of equilibrium is the chemistry of aqueous acids. Acid strength is measured by the pH scale.
There are many factors to consider when choosing a fuel. In this exercise, your group will work with a set of three different potential fuels and evaluate their performance in terms of price, energy density (per mole, per gram, and per volume) as well as in terms of CO2 emissions. You will then select which of your three fuels is the “best,” realizing that there are several possible considerations to select the “best” fuel. You will have to defend your choice, as well as your definition of “best!”