This 120 carbon atom graphite molecular model kit can build 4 layers of 6 member hexagonal rings. Each layer has the appearance of a honeycomb lattice similar to interconnected aromatic hydrocarbons.
The carbon atoms in these rings use 20mm bonds while inter-layer connections use 50mm. The longer, flexible bonds simulate van der Waals forces, bonds weaker than covalent. This allows manipulation of the model so that the layers can move slightly relative to each other.
These layers are arranged in 2 ways. The more common & stable alpha (hexagonal, right in image) is indicated as ABAB layer stacking. The less stable is the beta form (rhombohedral, left in image) indicated as ABCA.
Click on graphite models to see all model versions including a glow in the dark version, graphene sheets & nanotobes.
The bonds lengths of this model are 20 & 50 mm which are a close approximation of 0.142 nm C-C sp2 trigonal hybridized covalent bond lengths within the graphene layer & the 0.335 nm distance between layers. The model uses carbon atoms in their sp2 form but does not show any explicit double bonds. It can also be reconfigured in the form of a carbon nanotube or a single graphene sheet.
The common understanding of graphite has graphene layers able to move due to the weak van der Waals attraction between them. However, TEM images have shown that graphene layers are often joined at the edges which can restrict this motion. See: The closed-edge structure of graphite and the effect of electrostatic charging.
|68186-20||Wobbly bond, 20mm, each||152|
|68186-50||Wobbly bond, 50mm, each||35|
|68259C||Atom, Orbit, C "m", trigonal bipyramidal, black||120|