The density of hydrogen is 0.0000899 grams per cubic centimeter. It is the least dense of all gases and contains only one proton and one electron. However, its one electron is found in a shell that can hold two electrons, so hydrogen can bond with one other atom.
Hydrogen is so lightweight that it is uncommon in Earth's atmosphere, since it can escape the planet's gravitational pull. It is the most common element in the universe and is crucial to life, as it bonds with oxygen to create water. Hydrogen is also found in hydrocarbons, carbohydrates, methyl and ethyl alcohol, aldehydes, ketones, organic acids and esters.