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With Explore the Planets, investigate the planets, their moons, and understand the processes that shape them. By G. Jeffrey Taylor, Ph.D. See our DVD collection.
Shown here are four representations chemists use for propane, a common hydrocarbon. In the colored models, carbon is light gray and hydrogen is white.
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Windows to the Universe original artwork by Randy Russell.

Hydrocarbons

There is a large class of important chemical compounds whose molecules are made up entirely of carbon and hydrogen atoms. These compounds, as a group, are called "hydrocarbons".

Hydrocarbons are the critical energy storage molecules within all major types of fossil fuels (including coal, oil, and natural gas) and biofuels. They also form the feedstock for the production processes of many types of plastics.

Burning hydrocarbons in the presence of oxygen (O2) produces carbon dioxide (CO2) and water (H2O). If there is too much carbon or too little oxygen present when hydrocarbons are burned, carbon monoxide (CO) may also be emitted. Sometimes unburned hydrocarbons are released into the air during incomplete combustion.

Burning fossil fuels, including gasoline in automobile engines, releases some hydrocarbons into the air. In a typical urban environment, the atmospheric concentration of hydrocarbons is around 3 ppm (parts per million). Some hydrocarbons, along with other types of Volatile Organic Compounds (VOCs), contribute to the formation of photochemical smog.

The carbon atoms in hydrocarbons often form long chains or ring structures. Some of the hydrocarbons that you may have heard of include methane (CH4), butane (C4H10), propane (C3H8), benzene (C6H6), ethane (C2H6), and hexane (C6H14).

Last modified February 15, 2006 by Randy Russell.

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Our online store includes fun classroom activities for you and your students. Issues of NESTA's quarterly journal, The Earth Scientist are also full of classroom activities on different topics in Earth and space science!

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Most things around us are made of groups of atoms bonded together into packages called molecules. The atoms in a molecule are held together because they share or exchange electrons. Molecules are made...more

Oxygen

Oxygen is a chemical element with an atomic number of 8 (it has eight protons in its nucleus). Oxygen forms a chemical compound (O2) of two atoms which is a colorless gas at normal temperatures and pressures....more

Carbon Dioxide - CO2

Carbon dioxide is a colorless and non-flammable gas at normal temperature and pressure. Although much less abundant than nitrogen and oxygen in Earth's atmosphere, carbon dioxide is an important constituent...more

Carbon Monoxide - CO

Carbon monoxide is a colorless, odorless, tasteless gas. It is also flammable and is quite toxic to humans and other oxygen-breathing organisms. A molecule of carbon monoxide (CO) contains one carbon atom...more

Air Pollution

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Volatile Organic Chemicals (VOCs)

Volatile Organic Compounds or VOCs are organic chemicals that easily vaporize at room temperature. They are called organic because they contain the element carbon in their molecular structures. VOCs include...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA