Hydrogen is the lightest of all the elements. Each of its atoms has just one electron moving around one proton. Hydrogen accounts for about three-fourths of the mass of all the atoms we can see in the universe. On Earth, it is one of the elements in water (H2O), but as a gas it is only found in very small traces in our atmosphere. Since hydrogen burns easily in air and creates almost no pollution, it could become a fuel of the future.
FLOATS AND BURNS
Hydrogen is about 14 times lighter than air, so a balloon filled with hydrogen floats upward like a bubble in the heavier air around it. Many years ago, hydrogen was used in huge balloons and airships, lifting them up into the air. Since hydrogen catches fire easily when mixed with air, and even explodes, airships today use safer gases.
Hydrogen burns by combining with oxygen to produce water. A spacecraft’s rocket uses liquid hydrogen, along with liquid oxygen, as a fuel. These two elements are mixed in the spacecraft’s main rocket engines and then ignited.
As soon as hydrogen burns, it explodes, generating a thrust (a push with force) that lifts the spacecraft into space.
FUEL OF THE FUTURE?
hydrogen could one day replace gasoline and diesel as a vehicle fuel. It can be combined with oxygen from air inside a fuel cell, generating electricity for an electric motor. Hydrogen-fueled cars produce only water in their exhaust.
In the 1920s and 1930s, gigantic hydrogen-filled airships carried passengers across continents and oceans. Then, in 1937, the hydrogen in the German airship Hindenburg caught fire, probably from a stray spark. The massive fireball and explosion killed 36 people. Since then, airships have mostly used other, less flammable gases.