Hydrocarbon
In chemistry, a hydrocarbon is any chemical compound that consists only of the elements carbon (C) and hydrogen (H). They all consist of a carbon backbone and atoms of hydrogen attached to that backbone. (Often the term is used as a shortened form of the term aliphatic hydrocarbon.)
For example, methane (swamp/marsh gas) is a hydrocarbon with one carbon atom and four hydrogen atoms: CH4. Ethane is a hydrocarbon (more specifically, an alkane) consisting of two carbon atoms held together with a single bond, each with three hydrogen atoms bonded: C2H6. Propane has three C atoms (C3H8) and so on (CnH2n+2).
Liquid geologically-extracted hydrocarbons are referred to as petroleum (literally “rock oil”) or mineral oil, while gaseous geologic hydrocarbons are referred to as natural gas. All are significant sources of fuel and raw materials as a feedstock for the production of organic chemicals and are commonly found in the Earth´s subsurface using the tools of petroleum geology. Oil reserves in sedimentary rocks are the principal source of hydrocarbons for the energy and chemicals industries.
Hydrocarbons are of prime economic importance because they encompass the constituents of the major fossil fuels (coal, petroleum, natural gas, etc.) and biofuels, as well as plastics, waxes, solvents and oils. In urban pollution, these components–along with NOx and sunlight–all contribute to the formation of tropospheric ozone.
Usually carbon backbone is represented as molecular graph in which only carbon atoms are represented as vertices and bonds as edges. Molecular graphs contain the structure of the hydrocarbon in which missing hydrogen atoms can be added in a unique way. Hydrocarbons are extensively studied in mathematical chemistry.
There are essentially three types of hydrocarbons:
1. aromatic hydrocarbons, which have at least one aromatic ring
2. saturated hydrocarbons, also known as alkanes, which don’t have double, triple or aromatic bonds
3. unsaturated hydrocarbons, which have one or more double or triple bonds between carbon atoms, are divided into:
* alkenes
* alkynes
* dienes