Fluorine reacts with almost everything, glass included. In the 19th century, several chemists trying to isolate it were badly poisoned, and some died. Frenchman Henri Moissan finally succeeded in 1886 using low-temperature electrolysis, earning the 1906 Nobel Prize in Chemistry. Today, fluoride protects your teeth.
Cooled below −183 °C, oxygen turns into a pale blue liquid. Pour it between the poles of a strong magnet and, instead of flowing away, it hangs suspended between them. The reason lies in its unpaired electrons, which respond to the magnetic field. Liquid nitrogen, by contrast, is colourless and pours straight through.
In 2012, Felix Baumgartner jumped from a capsule hanging beneath a balloon, about 39 kilometres up. In that extremely thin air almost nothing slowed him down, and he reached around 1,358 km/h in free fall, or Mach 1.25. He became the first person to exceed the speed of sound with nothing but his own body.