Gin & Tonic Analogy of Hybridisation
Students often struggle with the concept of hybridisation, which is understandable, as it is insane (some chemists don’t believe it should be taught as it has no basis in ‘reality’ - we disagree, it makes understanding shape and reactivity easier so has a valid use).
Some students find the next analogy a helpful way in to hybridisation:
You start with four glasses. One is full of gin and the other three are full of tonic.
Now you mix them all together in a jug before pouring them back into the glasses.
You have the same amount of liquid as you started with but now you have four G&Ts (gin and tonics)
Each glass is 25% gin and 75% tonic. It is a (tasty) hybrid of the originals
- This is your sp3 gin and tonic.
Mixing four identical gin and tonics is the equivalent of forming four sp^3 hybrid atomic orbitals
It is possible to mix the drinks differently. We could mix the gin with just two of the glasses of tonic. We have started with the same amount of liquid and we will end with the same amount of liquid but we will get a different strength of G&T, or a different hybrid.
This time we have three glasses that are 33% gin and only 66% tonic. It’s a stronger drink. We also have a glass of pure tonic. As shocking as this may seem, this is still useful (perhaps someone is driving). This new hybrid is equivalent to an sp2 hybridised atomic orbital and the unmixed tonic is equivalent to a non-hybridised 2p orbital which can be used to create π bonds.
Mixing three identical gin and tonics is the equivalent of forming three sp^2 hybrid atomic orbitals - something is left-over
Finally, you may have had a really bad day (perhaps you had a chemistry lecture?) and need a strong drink. Now you are only going to combine the gin with one glass of tonic. Remember that the amount of liquid is conserved, you don’t spill any (chemistry labs do teach you practical skills). This will result in two strong glasses of G&T, each containing 50% gin and 50% tonic. There will also be two glasses of pure tonic. This is equivalent to the two sp hybridised orbitals and the associated two non-hybridised 2p orbitals.
Mixing two identical gin and tonics is the equivalent of forming two sp hybrid atomic orbitals
The funny thing about this analogy is we can stretch it further. It turns out that the weak sp3 gin and tonics will form weaker bonds than than the strong sp gin and tonics (a σ bond formed from the overlap of two sp HAO is stronger than a σ bond formed from the overlap of two sp3 HAO). The ratio of gin (or s orbital) makes a difference. The downside is chemistry is far more complex than mixing cocktails. If they aanlogy really held then hybridisation would cause the shape of the glasses to change!
There ends the analogy, I hope it is useful and if any gin distilleries are reading this, yes, I would love a free sample.
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