Nitrogen

I keep putting off writing this post.  Some of it is because I've been busy with other stuff, some of it is because I'm just plain lazy, and some of it is because there's so much to say about nitrogen.

Nitrogen is roughly 4/5 of our atmosphere, which is good, since if our atmosphere was pure oxygen, oxidation and combustion would be uncontrollable.  When you chill nitrogen down to -196 degrees, (Celsius of course...who in their right mind uses Fahrenheit anymore?) it liquifies, and you can do all sorts of cool things with it (like dip a rose in it and then shatter it against a counter, or make ice cream really really fast).  Hmmmm...run-on sentence.   But the most fun thing about nitrogen is its use in explosives.

Molecular nitrogen (N2) has a triple bond between the two nitrogen atoms.  This triple bond is very stable, and takes a lot of energy to break apart.  Conversely, if a reaction forms a N-N triple bond, a lot of energy is released.  This is why so many common explosives contain nitrogen atoms: ammonium nitrate, nitroglycerin, TNT (trinitrotoluene), etc.  These molecules form stable N2 when detonated, liberating a lot of energy in the process.

One particularly unstable nitrogen compound is nitrogen triiodide (NI3).  The three iodine atoms form a pyramidal shape around the lone nitrogen atom.

Nitrogen triiodide structure: blue for nitrogen, purple for iodine.

The large size of the iodine molecules lends some instability to this molecule, but what really makes it explosive is its decomposition reaction:  2 NI₃ (s) → N₂ (g) + 3 I₂ (g).  What this shorthand means is that two molecules of solid nitrogen triiodide react to form one molecule of gaseous nitrogen and three molecules of gaseous iodine.  A huge amount of energy is liberated in the formation of the N-N and I-I bonds.  As a result, nitrogen triiodide is a highly sensitive contact explosive, as demonstrated below:




Nitrogen triiodide can be made from fairly common household chemicals, and I've been itching to make some at home, but I'm not sure I can convince my wife that it's safe.  Is this why so many mad scientists stay single?