Recently, I was contacted on twitter by a concerned teacher who was using Chemistry Modeling Instruction for the first time. He was looking for supplemental materials to help his students understand why two atoms would form a covalent bond. His tweet sparked a conversation which eventually engaged some authors at AMTA (American Modeling Teachers Association). We agreed that our materials needed some work so several people started brainstorming and as a result we now have a new version of the MI teacher’s notes and a few new activities. These updated materials will be available to AMTA members this spring.
One of the resources we have vetted is an interactive slideshow from PBS on both ionic and covalent bonds. Teachers using Modeling Instruction will find these resources elucidate a model of electron behavior which adds to the particle story of matter we have been telling throughout the year. The ionic slideshow does a nice job explaining attraction and repulsion of different charges, and how ions arrange in a lattice formation. The interactive nature of the covalent slideshow helps students "see" how two electrons are shared between two hydrogen nuclei. Students can move the atoms around and watch how the nuclei repel each other while holding the electrons in the space between them.
The resources can be found on the PBS website at the links below: