3D modelling software is very good. There are some Java Applets that show 3D visualisations of orbitals. You just select whichever orbital you want and you can rotate it and view it from different angles.
Use models to illustrate shapes formed by molecules. Or use balloons to illustrate bonding pairs and electron pair repulsions leading to the determination of molecular shape You can show them a tetrahedron and an octahedron etc.
For this particular topic, there are some quite nice simulations of wave functions and of orbitals and similar things on the web that can be used to visualise what orbitals look like, and what wave functions look like. They seem to like it.
Use balloons to illustrate bonding pairs and electron pair repulsions leading to the determination of molecular shape For example, if you tie 6 balloons together, it automatically forms the octahedral shape. Then each time you pop one, they rearrange themselves to sequentially form the other shapes: trigonal bipyramidal, tetrahedral, trigonal planar and linear. It’s visually appealing, a concrete example and memorable for students. Also, popping the balloons wakes the students up!
Use Roy Tasker’s video model VisChem, or Kahn Academy, and post on Blackboard. There are a lot of online formative practise quiz questions, for example, in Kahn Academy.
Use Lego pieces. For example, HCl built out of Lego. Use a little blue brick and a yellow one, showing physically that on this side you’ve got one blue Lego brick and then on this side you’ve got two and so on, trying to make them see them not as chemical formulas but identities of some sort.
Try demonstrating the reaction first, to show the macroscopic changes that occur, before introducing the equation. Copper in silver nitrate solution is a standard one. Explain it in terms of particles, the ions, atoms, show a video representation (for example from YouTube) of these changes, and then explain the whole thing in terms of the symbolic chemical equation to represent the overall change.
You can use analogies to everyday objects and there are a variety of things you can use in that way, such as pebbles and peas to illustrate moles, because they have different masses. Certainly getting them to think about that and then to be comfortable in translating that into a whole lot of different elements you might be comparing.
