Every now and then, looking at my black and white cat reminds me of an organic chemistry tutorial I had with Jo Peach during my first year at Oxford.
We were talking about resonance, which Wikipedia describes as “a way of describing delocalized electrons within certain molecules or polyatomic ions where the bonding cannot be expressed by one single Lewis formula”. By which it means to say something like this:
…So we came up with the cat analogy. You see, resonance structures are black cats or white cats.
And by drawing resonance structures, we get a mental image of a black and white cat, the cat which is part of the black cat and part of the white cat mixed together into an amorphous two-tone cat.
And this is a problem, because the real structure is not a black and white cat. It is not a black cat or a white cat, it is a grey cat.
But drawing the grey cat is often not very useful in chemistry, which is why the cat anaology helps demystify resonance structures.
Sometimes, when you’re learning science, it’s good to come up with cat analogies, dirty mnemonics or silly names for things. Because it sticks. And now my black and white cat still reminds me of a tutorial I had five years ago!