An analogy for talking about Hund’s rule (where the p orbitals fill up) is that it’s like parents deciding where siblings will sleep. If you have enough rooms you put each person in one room because that's peaceful for everybody and everybody prefers that. If you have an extra child you have a choice of renovating your house, which is expensive and takes a lot of energy, or you put them in the same bedroom. You are going to put them in the same bedroom because you're not going to renovate your house. They get that.
In hybridisation, we have the idea that the energy at the atomic levels are changing - they're not going to be the same as an isolated atom on its own. Think about if you were sitting next to someone on the bus. You would sit there differently than if you were sitting there alone. If you're the only person on the bus and then somebody else gets on the bus, how would you feel if they came and sat right next to you? We know instinctively they wouldn't do that. Electrons are a bit the same. They won't sit in the same spot. Once all the seats have someone in them then they’ll sit next to you.
Particularly for the VSEPR theory, models of any kind are great. Tell the students, 'Buy a model kit.' Because it has to be something three-dimensional. They need to bring their own models in so they can do it themselves.
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.
When teaching electronic configuration, if it's a small class you can get each student in the class to be an electron. They can arrange themselves in different directions. It's really good if you've got steps in your classroom because you can demonstrate going up in energy. They face towards the front or the back of the room. If you simply tell them to think about parallel and antiparallel spins they come up with that themselves and it's really good when you can say, 'Yes, you came up with that yourselves.'
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!
