Silfa Zoidberg, via Facebook asked:
I don't understand why graphene is considered 2-dimensional. One atom thick is one atom thick... No? Why do we call it 2-dimensional when clearly, it has a third dimension?
We posed this question to Dr. Karl Coleman from Durham University...
Karl - I guess you could argue it has a third dimension, but, one atom thick is really the thinnest you can go. So, I would argue that it is negligible in thickness in one direction and that is why we call it a 2-dimensional material and graphite of course would be the 3-dimensional version where you have several layers that make up the structure. So basically, you can't get thinner than one atom I would argue.
Dave - And I guess also, the electrons actually have a wavelength, so in effect something a bit like a size and the wavelength is of the order of the thickness of the graphene. So, to the electron, it does look like a 2-dimensional thing because it is as thick as they are.
Karl - It is. It is confined in that 2-dimension. You're right, yes.