Sodium is a soft metal that bursts into flames on contact with water. Chlorine is a greenish gas once used as a chemical weapon. Put them together and the reaction is violent and dazzling, producing sodium chloride, the salt you sprinkle on your fries. A compound can behave nothing like the ingredients it is made from.
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.