Antimony Tellurium Iodine Xenon Cesium Blank Fluorine Chlorine Bromine Iodine Astatine Ununseptium
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Contact Explosives

One of the things you can do with iodine is to dissolve it in liquid ammonia and then let the solution evaporate away on some filter paper (or a paper towel), leaving a residue of nitrogen triiodide. I won't give you the exact directions here, but you won't have a problem finding them if you have any business trying the experiment. The reason for this intelligence test is that nitrogen triiodide is a contact explosive: When dry, the slightest disturbance causes it to explode violently.

Back in the very early days of Wolfram Research, Inc, not long after we had released the first version of Mathematica, one of the original members of the company (who shall remain nameless but it wasn't me) decided that it would be fun to attach some nitrogen triiodide to the front end of a small radio controlled car. Who wouldn't?

I should mention that this was the same person who was responsible for the German marching music piped over the intercom system and for helping blow up my friend Donald's bean field one evening. So when he decided to make a toy car bomb, it was not on a small scale. The liter of liquid ammonia was so pungent one simply could not enter his office (yes, office).

Once nitrogen triiodide is dry, it will explode literally at the touch of a feather (here's
a video showing exactly that from the Journal of Chemical Education's website). So it had to be created in-situ, by scotch taping some folded up paper towels, wet with iodine-ammonia solution, to the end of the car, setting it in place, and then letting it dry without further disturbing the car.

In those days the company was housed in a round building and our main machine room was one complete half-circle of one floor, with no internal divisions. In the early morning light (having worked all night, of course, not come in early) the room reminded me of nothing so much as the scriptorium described in Umberto Eco's The Name of the Rose. In place of rows of monks bent over their illuminated manuscripts was a majestic arc of engineers bent over every size and description of micro- and mini-computer, curving off into the distance. Of course, this room was also the perfect place for ramming some unfortunate object with a front-loaded demolition car.

I have to admit, after this buildup, that the actual explosion was a bit anti-climactic. It did send the car backwards at some speed, and didn't do its front end any good, but hardly any serious physical damage was done, much to the disappointment of all concerned.

If you decide to try anything similar, remember that nitrogen triiodide is not only unbelievably sensitive, the more so the more dry it is, it's also a high explosive. That means it detonates so quickly that it forms a supersonic shock wave capable of ejecting bits of broken plastic, or whatever, at high speeds, even if it is not confined. This makes it significantly more dangerous than, say, gunpowder, which can only cause that kind of shrapnel if it is tightly confined when ignited.
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