Useful models

These amazing pictures were taken at the University of California using an atomic force microscope, this device effectively probes the surface of a material with a very fine "needle" and measures the forces of attraction/repulsion to derive an image of what it finds, much like the tip of a gramophone needle riding in the groove of a record. The tip of this needle is actually a single molecule so the resolution is pretty fine, these pictures are showing a single molecule undergoing a reaction, i.e.  detailing the intermediate forms and bonds of the atoms as the reaction progresses. It's astonishing that the images show molecules looking remarkably similar to the stick models we used to use in Chemistry lessons, some bright spark in the past clearly latched onto the right idea for modelling these things.