The physical properties of hydrocarbons ­ whether they are gases or liquids, how easily they catch fire, and how they burn ­ depend on their chemical structure.

All types of hydrocarbons contain a series of carbon atoms which are linked together. Each type of hydrocarbon has its own unique length of "carbon chain", and the length influences what form each substance takes.

Hydrocarbons with short carbon chains tend to be gases, and those with long chains of more than 10 carbon atoms, tend to be liquids. The simplest carbon compound found in natural gas is methane, which contains only one carbon atom and is normally a gas. Its chemical shorthand is CH4, which stands for one carbon and four hydrogen atoms.

Hydrocarbons are often referred to by the number of carbon atoms they have. For example, propane (the gas used in barbecues) is a 'C3' hydrocarbon ­ it contains three carbon atoms. Lubricating oil, on the other hand, is a mix of 'C26' to 'C40' hydrocarbons, with much longer chains of 26 to 40 carbons.

Information provided by: http://ycn.library.ns.ca