As you already know, hydrocarbons are chemical compounds of hydrogen and carbons. Hydrocarbons are not artificially made; they occur naturally by plants and animal fossils after millions of years. They are mostly found deep underground in porous rock formations, which are mainly under the oceans. The molecular formula of hydrocarbons in a general context is C_xH_y. This molecular formula tells you that there will be some carbon atoms(x) and some hydrogen atoms(y).

Earlier, the hydrocarbons were classified based on their source and properties, but today we classify them on the basis of structure.

So you may ask how many types of hydrocarbons are there today?

Today we have 2 main types of hydrocarbons Aliphatic or Acyclic and Alicyclic. These two also have subtypes Saturated, and Unsaturated are subtypes of Aliphatic, whereas Homocyclic and Heterocyclic are subtypes of Alicyclic.

1) Aliphatic Hydrocarbons: –

An aliphatic compound is a compound of hydrocarbons containing carbon and hydrogen joined together in a straight chain. This means there is no component joined in the side chain. The simplest aliphatic hydrocarbon is Methane (CH₄).

• Saturated Hydrocarbons: –
  You need to know first what saturated means. It means where no addition is allowed. So, with respect to saturated Hydrocarbons, there can be only one carbon-carbon bond, and no addition is allowed. These are saturated hydrocarbons. Butane (C₄H₁₀) and octane (C₈H₁₈) are the most common examples of saturated hydrocarbons.
• Hydrocarbon Alkanes and Cycloalkanes: –
  A saturated hydrocarbon can have a linear, ring-shaped or branched structure, so hydrocarbon alkanes and cycloalkanes also come under saturated hydrocarbons. Hydrocarbon alkanes only contain single-bonded carbon and hydrogen atoms. Hydrocarbon alkanes have a molecular formula C_nH_2n+2. Hydrocarbon alkanes are the least reactive hydrocarbons which only contain carbon and hydrogen. So it does not contain double or triple bonds.
  Cycloalkanes are mostly artificially created in the laboratory containing rings of carbon atoms with distinguishable chemical properties. The carbon atoms in cycloalkanes are joined in a ring structure. The general formula for cycloalkanes is C_nH_2n. Examples of cycloalkanes are cyclopropane (C₃H₆), cyclobutane (C₄H₈), cyclopentane (C₅H₁₀), cyclohexane (C₆H₁₂), etc.

2) Hydrocarbons Alkene: –

Hydrocarbon alkenes have carbon-carbon double bonds. Hydrocarbon alkene has fewer hydrogen atoms than hydrocarbon alkanes. Hydrocarbon alkene is an unsaturated hydrocarbon. It has a molecular formula C_nH_2n. Some common hydrocarbon alkenes are ethene (C₂H₄), propane (C₃H₆). The melting point of alkene is -169^oC and boiling point is – 104^oC, and that of propene are – 185^oC and – 47^oC. Ethene is used to produce polyethylene (polythene), a plastic. Propene is used to make plastic isopropyl alcohol and many other products.

3) Hydrocarbons Alkyne: –

Hydrocarbons Alkynes are made up of carbon-carbon triple bonds. The molecular formula for hydrocarbon alkyne is C_nH_2n-2. Triple bonds are considered to be very strong bonds. Examples of hydrocarbon alkynes are ethyne (C_zH₂), propyne (C₃H₄), butyne (C₄H₆), pentyne(C₅H₈), etc.

4) Hydrocarbons Aromatic: –

Hydrocarbons aromatic are unsaturated hydrocarbons. They have one or more than one planar six-carbon ring to which hydrogen atoms are joined. This cyclic ring is called the benzene ring.

The hydrocarbons have different molecular formulas from each other because of the different molecular structures they possess. Hydrocarbon alkynes and hydrocarbon alkenes have less bonded hydrogen due to catenation (ability to bond to themselves) of carbon. This is what prevents doesn’t allow the complete saturation of hydrogen, forming double or triple bonds. With such properties, they can also form very complex molecules like cyclohexane and sometimes benzene.

There is a concept of cracking of hydrocarbons where complex hydrocarbons or kerogens are broken down into smaller and lighter hydrocarbons by breaking the carbon-carbon bonds. This process is used in making petrol, diesel, and gasoline. 

Physical properties of Hydrocarbons: –

1. Hydrocarbon alkanes and hydrocarbon alkenes have a lower melting point than hydrocarbon alkynes.
2. Hydrocarbon alkanes or hydrocarbon alkenes have a weaker force of attraction than hydrocarbon alkynes.
3. No other molecule than carbon or hydrogen is present in hydrocarbons.

Chemical properties of Hydrocarbons: –

1. Hydrocarbon alkanes don’t react with more compound variety than hydrocarbon alkenes.
2. Hydrocarbon alkenes or hydrocarbon alkynes perform additional reactions, whereas hydrocarbon alkanes practice substitution.
3. Hydrocarbon alkanes have a single bond.
   Hydrocarbon alkenes have a double bond.
   Hydrocarbon alkynes have a triple bond.

Uses of Hydrocarbons

• Hydrocarbons are very much used in fuels like LPG and CNG.
• Hydrocarbons are used to serve as lubricating oil and grease.
• Hydrocarbons are used in the manufacturing of polymers like polyethylene, polypropylene, polystyrene, etc.
• Hydrocarbons are also used in manufacturing drugs and also dyes as a starting material.
• Ethane is mainly used to produce ethylene.
• Hydrocarbon Gas Liquids (HGL) are used in residential, commercial, industrial, transportation, and electric power.

1) What are the four types of hydrocarbons?

Ans.: – There are four main types of hydrocarbons Alkanes, Hydrocarbon Alkenes, Hydrocarbon Alkynes, and Hydrocarbon Aromatic.

2) What are the five common hydrocarbons?

Ans.: – Common hydrocarbons are Methane, Ethane, Propane, Butane, Pentane, and Hexane.

3) What are hydrocarbons used for?

Ans.: – Hydrocarbons are used as the principal constituents of petroleum and natural gas. They are also used in the production of plastic, fibres, rubbers, solvents, etc.

4) Which hydrocarbon is the most flammable?

Ans.: – The hydrogens with small hydrocarbon chains are highly flammable due to a higher amount of carbon-hydrogen bonds than carbon-carbon bonds.

5) How do you identify hydrocarbon?

Ans.: – You have to look for a class of chemical compounds with only one element of carbon and hydrogen.