For some reason, everyone seems to have an obsession with knowing exactly which chemicals are the most explosive, the most volatile, the most acidic. In short, which chemicals are the most dangerous. So, here's a list of just that; five of the most dangerous chemicals known to man, with some explanation of what they're capable of doing.
Substance N (Chlorine Triflouride)
When something is first developed by the Nazi's as a war weapon, you know it has to be pretty nasty stuff. Substance N, as it was code-named by the Nazi scientists who synthesized it, was the chemical Chlorine Triflouride, the most violently flourinating agent known to man. Whilst that may not sound impressive, what Substance N does explodes on contact with water, evaporates on contact with air, is deadly to inhale and when it decomposes to give out a toxic acid. The plan was to load Substance N into flamethrowers, where it would burn at over 2400 degrees Celsius, but the Nazi's decided that it was too dangerous to use. Experiments with Substance N were then stopped, but it is still regularly produced and used by semiconductor companies to clean their equipment. Substance N is even capable of burning things that are not even normally considered flammable, including bricks, asbestos and even things that have already been burnt!
Yes, this is really the name of the next chemical on the list. Azidoazide Azide is the single most explosive compound in the world. On a chemical level, this is because Azidoazide Azide stops Nitrogen ions from coming together in the way that they want to, which the Nitrogen ions resent, and they just take the tiniest of knocks to snap into place, which releases a whole lot of energy; an explosion. Attempts have been made to measure just how much of a knock it takes to set the explosion off, but they have failed, as even the smallest touch the instruments the US military used set off the explosive decomposition. Things that can cause Azidoazide Azide to explode include: moving it, touching it, leaving it alone on a glass plate, exposing it to bright light or x-rays, putting it in a spectrometer, turning on the spectrometer, or even absolutely nothing. On one occasion, a sample was stored in a shock-proof, explosive-proof case, in a dark, climate controlled room and, it blew up.
Dimethylcadmium does set on fire, but the main reason that it is so dangerous is it's toxicity; it has chronic and acute effects, meaning that coming into contact with it will not only kill you in the short term, but in the long term as well. On touching it, it is instantly absorbed into your bloodstream, where they travel around your entire body, quickly affecting the most blood infused organs. Then, it creates compounds that tear the electrons off the atoms of the cells. Even if, somehow, you do manage to survive the first few hours, Dimethylcadmium is exceptionally carcinogenic, which means that cancer will get you further down the line. Oh, it also explodes on contact with water or with friction and it decomposes to give another highly explosive compound.
Thioacetone won't give you cancer, start fires, or even explode. What it does do is smell bad. Really, really bad. It's chemical composition is similar to that of chemicals used in a skunk's spray. The other part of it's chemical make up is like that of the smells that come out of rotting meat, so not a great combination. One drop can be smelt nearly instantaneously from 500m away. In 1889, scientists were working on a larger chemical, but accidentally caused Thioacetone to be formed in a soap factory. Workers fell sick and people in the surrounding neighborhoods began to vomit and soon the entire German city of Freiburg, the site of the spill, had to be evacuated.
The most corrosive acid known to mankind is the final entry on the list. What makes an acid an acid is it's ability to undergo protonation, and it's strength is how easily it undergoes this process. For a little sense of scale, Fluoroantimonic acid does this 10,000,000,000,000,000 (10 quadrillion) times better than Sulfuric acid, which is a pretty nasty thing to spill on yourself. After undergoing protonation, the remaining elements rip the electrons from surrounding elements, leaving a pile of organic goo in it's wake. If you do get some of this on yourself, after it burns up your skin, it will then eat through your bones. Again, the very properties that make it interesting make it hard to test; you can't put something in a syringe if it will simply burn through it.
Which is the most dangerous? Well it depends on how you would prefer to die, as most of these chemicals, if you are exposed to them will kill you, and, perhaps more worryingly, there is nothing that science can do yo save you.