When news of Syria’s chemical weapons possession surfaced amid their civil war, the Obama administration and the United Nations were in an uproar. The weapon is indisputably one powerful enough to obliterate an enemy, and could have heightened the death toll to an even more devastating rate, had the U.S. not successfully destroyed the Syrian government’s stockpile in August. Dating back to WWI, when the Germans used chlorine and phosphine gases against the French, which resulted in over 90,000 deaths, chemical weapons have been a sure-fire way to retaliate. SciShow’s YouTube video “5 of the World’s Most Dangerous Chemicals,” however, takes you through a run-down of some chemicals so dangerous that even the most volatile enemies in WWII, like the Nazis, abstained from using them.

Chlorine trifluoride (CLF3), a fluorinating agent, was the chemical the Nazis quickly learned could easily wipe out their own troops. Although they had originally planned to produce 90 tons per month of the chemical, they ultimately produced 30 tons by the end of the war. CLF3 is more powerful than fluorine gas, which, as our SciShow host puts it, “is not a sentence you get to say very often.”

In fact, all of the chemicals SciShow runs through are deadly enough even a millionth of a gram can kill you. They are the most explosive, toxic, and even smelliest in the world.

Take azidoazide azide, for example, which is extremely reactive and explosive. Simply exposing it to bright light, touching it, or “absolutely nothing” can make it blow your head off. A team of scientists had it stored in a shock-proof explosive case, and it still exploded.

Learn about SciShow’s other three insanely lethal chemicals in the video.