Space-filling molecular models: Nitrogen expansion set

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Nitrogen generally can make three bonds to other atoms, but it has one pair of electrons which do not take part in the bonds but which also have to take up space. The three bonds and the "lone pair" electrons generally take the form of a tetrahedron, but if the lone pair is in the vicinity of a double bond, it re-arranges itself to contribute to the double bond and the bonded atoms re-arrange into a planar triangle (no bonds have to be broken to do this). So the 3D arrangement of nitrogen compounds is all about where the lone pair is. Nitrogen6 is the tetrahedral form, while NitrogenSP21 is the planar form. There are also double and triple bonded nitrogens, but most of these are for more esoteric compounds. Compounds with double-bonded nitrogens are often called diazo or other equally weird names, use Nitrogen DB1 for this; the bottom socket represents the double bond,technically this bond doesn't rotate, but it's complicated. Nitrogen can form a triple bond with carbon to form nitriles, which are also known as cyanides (popular with the murder mystery set {by the way, cyanide doesn't smell like bitter almonds; don't ask me how I know, but suffice it to say I lived to tell about it}). Elemental nitrogen in the air is also triple bonded to itself. Use NitrogenTB1 for this. Nitrogen can also form four bonds, but this is then positively charged. Use the appropriate carbon atoms for this, in of course the appropriate color (they're the same size and shape). See the starter set (http://www.thingiverse.com/thing:1720048), the carbon expansion set (http://www.thingiverse.com/thing:1730299), the aromatic expansion set (http://www.thingiverse.com/thing:1754393), 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. Print Settings Printer: Da Vinci 1A Rafts: Doesn't Matter Supports: Doesn't Matter Resolution: 0.2 mm Infill: 10% Notes: Three perimeters works well.