sentence: Pure hydrogen is very uncommon in the Earth's atmosphere.
sentences_after: In nature, it is usually in water. Hydrogen is also in all living things, as a part of the organic compounds that living things are made of. In addition, hydrogen atoms can combine with carbon atoms to form hydrocarbons. Petroleum and other fossil fuels are made of these hydrocarbons and commonly used to create energy for human use.
concept_name: pure hydrogen
headings: Hydrogen Hydrogen in nature
categories: Nonmetals