Expert Insights

When you think of things in terms of energy you can represent energy … energy can be modelled as a particle, as matter.  It can be modelled using waves and then trying to talk about how we would use each model as it's appropriate for a particular situation.  It's the sort of things we observe might dictate which model we use to explain it, by recognising that in each case there is another model but perhaps just not as useful.  So maybe it goes back to just trying to show that everything that we do is a model, every model has its upside and its downside and that we usually only use a model that’s as detailed as it needs to be for the particular concept that you're trying to get across.  If you want to get across a concept of a car to someone who has never seen a car you don't probably show them a Ferrari or a drag racing car.  Maybe you show them a Lego style block and we do the same thing with our scientific models as well.  I guess trying to get across that idea that this is the model that we're going to use but it can be a lot more complicated.  I don't want you to think it's as simple as this but it's appropriate under the circumstance.  So I guess I spend a lot of time talking about things as models when I'm talking about quantum mechanics.  Our treatment in the first year, which is where I cover it, a little bit of second year but I don't take a mathematical detail treatment of quantum mechanics.  Someone else does that, so I really bow to them. So most of mine is non-mathematical, just simple mathematics and mainly conceptual type of stuff.  I guess some of the things I try and do to illustrate the differences between the models and the way that we use them is to ask questions in class that might be postulated in such a way that you can't answer it if you're thinking about both models at the same time.  So the one I like is where I show say a 2s orbital and the probability distribution of that node in between.  I talk about things that … there's one briefly, this plum pudding model which they all laugh about.  When you look at this 2s model there is a probability and a high probability, relatively so, that the electron can be inside the nucleus, if you think about it in particle terms.  Then talk about the nodes and so on and how they arise in quantum mechanics and so on and then ask questions like if the electron can be here and here but it can never be here how does it get there?  ...  I try and get across maybe the bigger picture, everything we're going to do from this point on (because we do this fairly early in first year)  - everything 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 will be just a model. You'll hear us saying things like ‘this is how it is’ or ‘this is what's happening’.  But really you need to interpret that as ‘this is a model and this is how this model is used to explain this particular phenomenon.

The actual curly arrow mechanisms are in a way themselves cartoons, how they map to the reality in the way that a Micky Mouse might map to real life.

In the lecture theatre the best strategy there, where you’re confronted by all the constraints of the lecture theatre, is to stop and do stuff with the students, walk around amongst them, see what they’re actually doing... And out of that you might go back and address some aspect of it and revisit it or something like that or you might point them to some tools to use to work out some other aspect.  So in the lecture theatre it’s very much for me a case of stopping and going and seeing what they’re doing and if you don’t then clearly you don’t know. 

Ions and ionic chemistry are essential to life and just about everything they will run across.

So, it’s helping to bed down analysis, problem solving, doing the sort of detective work to get to an answer.  And the students also seem to quite enjoy having material presented to them in that way - here’s a spectrum, what do you think the structure is, because it’s a more active form of learning as well.  So I find I enjoy teaching it, and they respond well in terms of, they keep coming in and asking me for additional problems to practise on which is clearly evidence that they feel it’s challenging them.

[Analytical chemistry] is probably one of the things that’s easiest to tie back to their own experiences.  Because it’s very easy to link the idea of the importance of chemical measurement, is actually pretty easy to get across. You just talk about what is sports drug testing, road side testing, when was the last time you went to the doctor to get a path test.  These are all forms of analytical chemistry.  So I have a significant advantage over some people [teaching other topics] in being able to imbed it in their experiences.  Everybody has some kind of experience we can draw on to say, yeah that’s analytical chemistry.  The difficulty is of course to ensure that misconceptions don’t creep in.

I find that some students pick up what the mole concept is from the idea of grouping numbers of things that are every day size. 

I think personally the quicker the students can see that holistic approach to chemistry the better... Because that’s when they start to realise how cool it is.

We all spend a certain amount of our class time going through definitions and jargon and getting students up to speed with the basic area and now that’s material which I take out of the class and put online and let students read and understand that in their own time before they come to the class.

I have one slide where I'm first demonstrating how we use curly arrows and that shows an arrow going in a particular direction from a nucleophile to an electrophile and emphasising that the arrow shows electrons moving - so it's got to start from where they are.  There has to be some electrons there for them to move.  So the whole screen goes black and comes up with a little orange box of 'never do this' which is an arrow starting from an H+, which has no electrons. The dramatic emphasis that the whole room goes dark and then it's just up there.

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