Hydrogen is the most simple and light element in the universe. It is made of one proton and one electron (there is no neutron). Because it is so simple, it is believed by some people to be the root of all the elements. Hydrogen is 14-15 times lighter than air, so when it escapes, it floats immediately up into the atmosphere. This means that it won't soak into the ground to pollute the groundwater, it won't sink into your clothes, and if there is a spill, it won't pool up on the ground like gasoline would. It simply removes itself! Hydrogen is the most abundant element in the universe, as it makes up over 90% of all matter. Even on Earth, it is one of the three most common elements, and is found in water and all organic matter.