HYDROCARBONS

 What is a Hydrocarbon?

The term hydrocarbon refers to an organic chemical compound that is composed exclusively of hydrogen and carbon atoms. Hydrocarbons are naturally-occurring and form the basis of crude oil, natural gas, coal, and other important energy sources. They are highly combustible and produce carbon dioxide, water, and heat when they are burned. As such, hydrocarbons are highly effective as a source of fuel. Hydrocarbons are organic compounds that contain only carbon and hydrogen. The four general classes of hydrocarbons are Alkanes, Alkenes, Alkynes, and Arenes. Aromatic compounds derive their names from the fact that many of these compounds in the early days of discovery were grouped because they were oils with fragrant odors.

Types of Hydrocarbon

Alkanes

Alkanes are organic compounds that consist entirely of single-bonded carbon and hydrogen atoms and lack any other functional groups. Alkanes have the general formula CnH2n+2$C_n{H}_{2n+2}$ and can be subdivided into the following three groups: the linear straight-chain alkanes, branched alkanes, and cycloalkanes. Alkanes are also saturated hydrocarbons. Alkanes are the simplest and least reactive hydrocarbon species containing only carbons and hydrogens. They are commercially very important, being the principal constituent of gasoline and lubricating oils and are extensively employed in organic chemistry; though the role of pure alkanes (such as hexanes) is delegated mostly to solvents. The distinguishing feature of an alkane, making it distinct from other compounds that also exclusively contain carbon and hydrogen, is its lack of unsaturation. That is to say, it contains no double or triple bonds, which are highly reactive in organic chemistry. Though not totally devoid of reactivity, their lack of reactivity under most laboratory conditions makes them a relatively uninteresting, though very important component of organic chemistry. 

Alkenes

Alkenes are a class of hydrocarbons (e.g, containing only carbon and hydrogen) unsaturated compounds with at least one carbon-to-carbon double bond. Another term used to describe alkenes is olefins. Alkenes are more reactive than alkanes due to the presence of the double bond.Alkenes contains a carbon-carbon double bond. This carbon-carbon double bond changes the physicals properties of alkenes. At room temperatue, alkenes exist in all three phases, solid, liquids, and gases. Melting and boiling points of alkenes are similar to that of alkanes, however, isomers of cis alkenes have lower melting points than that of trans isomers. Alkenes display a weak dipole-dipole interactions due to the electron-attracting sp2carbon.

Alkynes

Alkynes are organic molecules made of one ore more carbon-carbon triple bonds. They are unsaturated hydrocarbons and are written in the empirical formula of 

CnH2n−2

Hybridization due to triple bonds allows the uniqueness of alkyne structure. This triple bond contributes to the nonpolar bonding strength, linear, and the acidity of alkynes. Physical Properties include nonpolar due to slight solubility in polar solvents and insoluble in water. This solubility in water and polar solvents is a characteristic feature to alkenes as well. Alkynes dissolve in organic solvents.

Arenes 

Arenes are aromatic hydrocarbons. The term "aromatic" originally referred to their pleasant smells (e.g., from cinnamon bark, wintergreen leaves, vanilla beans and anise seeds), but now implies a particular sort of delocalized bonding. Aromatic hydrocarbons (or sometimes called arenes or aryl hydrocarbon) are hydrocarbons with sigma bonds and delocalized π$\pi$ electrons between carbon atoms forming rings.Aromaticity is a property of conjugated cycloalkenes in which the stabilization of the molecule is enhanced due to the ability of the electrons in the π orbitals to delocalize. This acts as a framework to create a planar molecule.

Types of Hydrocarbons

Understanding Hydrocarbons

Hydrocarbons occur naturally. They originate from plant and animal fossils that were formed by the forces of temperature and weight over millennia. They are mostly found deep underground, in porous rock formations, such as sandstone, limestone, and shale.

Hydrocarbons are very important for the modern economy. They are responsible for more than 80% of global energy consumption. This figure may actually understate the role of hydrocarbons in the economy by a significant margin because they are used in a wide range of applications aside from their use as a source of energy. For example, refined petroleum has been used to produce many derivative materials that play critical roles in the global economy, such as plastics, solvents, and lubricants.

Different techniques are used to extract hydrocarbons, depending on the type and location of the reserve. For example, hydraulic fracturing (better known as fracking) is used to extract natural gas from shale rock by using pressurized fracking fluid to create fissures through which the gas can escape to the surface. Mining is used to access oil sands, which are unconventional deposits of crude oil that are heavily intermixed with sand and sandstone.

Hydrocarbons

References: 

Hydrocarbons: Definition, Companies, Types, and Uses

Hydrocarbons - Chemistry LibreTexts