Models and Representations

Pebble Demonstration for Moles

Take something into the lecture theatre, like a bag of pebbles - a whole lot that are the same size and make sure that it is visibly a kilogram (or another specified mass). Also have chickpeas or some other smaller and lighter thing. When you have a kilogram it’s really easily recognisable that there’re a lot more particles in the chick pea bag that there are in the pebble bag. You can’t show them a mole of something because it’s too many, but just use this to begin to unpack the idea that we’ve got a whole lot of tiny, tiny particles, much smaller than the ones in the demonstration.

Concept Map the Calculations

The way back-titrations are taught is often confusing. Get them to concept map the calculation. So, instead of trying to do the calculation in their head, map it out starting from where they end up, and then relate each of those steps to where that number is coming from. Have them think about it like it’s a reaction. Because they know how to do the math, and they can understand how to do it for a reaction. An example is the dissolution of calcium carbonate and trying to get them to work out how much carbonate is in a limestone sample.

A Series of Models

Try and get across the bigger picture - everything you're going to do is going to be a model. Nothing is going to be right. Nothing is going to be wrong. Nothing is going to be exactly the way it is. Everything is a series of models.

Particle-Wave Duality

Try to show students that the fundamental form of matter is energy. Then that this can be represented as particles with mass or as waves (wave functions). Link to YouTube Video: Particles and Waves

Using Models

Use molecular models, simulations, Lewis diagrams, ball and stick models, space filling models. Different representations - macroscopic and microscopic. Make sure you know how to use them.

Link to YouTube Video: Bonding Models and Lewis Structures

 

 

Visualise Water in Different States

Use the Vis Chem website, which is Roy Tasker’s resource, and there are links to a Scootle site where you can download visualisations for chemical bonding and pure substances in different states. There is gaseous water and liquid water. You can see they’re close together - they’re crowded. You can talk about ice skating. You can press the ice and it becomes liquid. That’s why the ice skates slide. You can see they’re jiggling away. There’s some space between them.    

Link to VisChem     

Quantum Mechanics for Large Objects

We describe quantum mechanics for an electron, but when it’s a tennis ball, what would the equation look like? This gives them the idea that the model works for every kind of particle.

Real Life Applications

Relate material to real-world applications, for example, the ‘Particle in a box’ model for cyanine dyes.

Link to Particle in a Box PDF

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