Space-filling molecular models: Aromatic expansion set

When we say "aromatic" compounds, that doesn't necessarily mean they smell nice (most do have a distinctive scent, but like most chemicals you're not supposed to go out of your way to smell them). "Aromatic" is chemspeak for certain flat, ring-shaped compounds with alternating double bonds. The double bonds exist out of the plane of the ring and interact (delocalize) in such a way the it's as if all the atoms are connected by 1 1/2 bonds and the resulting compound is particularly stable. You usually see six-membered rings, most of them made of carbon. This also happens to five-membered rings, but at least one atom needs to be something other than carbon ("heterocyclic" in chemspeak). Frequently this is nitrogen, but other atoms can do this also. So, to make six-membered aromatic rings, use CarbonPH6 and NitrogenPH1. To make five-membered rings use Carbon5PH1 and Nitrogen5PH1 (there's a "5" on these to help tell them from the six-membered ones). Usually nitrogen can't bond to atoms outside the ring because generally all three bonds are taken up to make the ring bonds. Occasionally this isn't the case. In that case, use the appropriate carbon model and print it in your nitrogen color. (they're the same size and shape). You frequently get two rings joined together; this lets the delocalized electrons extend over both rings, which results in a particularly stable molecule. Use CarbonJPH1 to join two six-membered rings. For even more complicated compounds you may need CarbonIPH1 also because the double-carbon unit may not fit. To join a five and a six-membered ring together, use Carbon56PH2. You can have to joined five-membered rings, but they're rare and I felt lazy.

See the starter set (http://www.thingiverse.com/thing:1720048), the carbon expansion set (http://www.thingiverse.com/thing:1730299), the nitrogen expansion pack (http://www.thingiverse.com/thing:1753583), halogen expansion set (http://www.thingiverse.com/thing:1730099), and the sulfur and phosphorous expansion set (http://thingaverse.com/thing:2350618) for more useful elements.