Chemistry - Carbon and its Compounds



  • Carbon plays very important roles for all living beings.

  • The amount of carbon in the earth’s crust is merely 0.02%, which is available in the form of minerals such as carbonates, hydrogen-carbonates, coal, and petroleum.

  • The presence of carbon in the atmosphere of the earth is 0.03%, in the form of carbon dioxide.

Compounds of Carbon

  • Almost all carbon compounds (except a few) are poor conductors of the electricity.

  • The diamond and graphite both are formed by carbon atoms; however, the difference lies between them in the manner in which the carbon atoms are bonded to one another.

  • In diamond, each atom of the carbon, is bonded to four other carbon atoms and form a rigid three-dimensional structure (see the image given below).

Diamond Structure
  • In graphite, each atom of the carbon, is bonded to three other carbon atoms in the same plane, which gives a hexagonal array (see the image given below) −

graphic Structure
  • There is also difference in some physical structure of diamond and graphite.

  • Diamond is the hardest substance known whereas graphite is smooth and slippery substance.

  • Graphite is good conductor of electricity whereas diamond is not.

  • Following table illustrates the structures of compounds of carbon and hydrogen −

Name Formula Structure
Methane CH4 Methane Structure
Ethane C2H6 Ethane Structure
Propane C3H8 Propane Structure
Butane C4H10 Butane Structure
Pentane C5H12 Pentane Structure
Hexane C6H14 Hexane Structure
  • The compounds, which has identical molecular formula, but different structures, are known as structural isomers (see the structure Butane given below).

Structure Butane
  • The saturated hydrocarbons are known as alkanes.

  • The unsaturated hydrocarbons, which comprise of one or more double bonds, are known as alkenes.

  • The unsaturated hydrocarbons, which comprise of one or more triple bonds, are known as alkynes.

Use of Alcohol as Fuel

  • Sugarcane plants very efficient convert sunlight into chemical energy and its juice can be used to prepare molasses.

  • When molasses is fermented, it produces alcohol (ethanol).

  • Some of the countries now using alcohol as an additive in petrol, as it is a cleaner fuel.

  • These alcohol, on burning in sufficient air (oxygen), gives rise to only carbon dioxide and water.


  • Esters are sweet-smelling substances, which are most commonly formed by reaction of an acid and an alcohol (see the image below – illustrating the formation of esters).

Formation of Esters
  • When esters react in the presence of an acid or a base, it gives back the alcohol and carboxylic acid.

  • The reaction of esters with an acid or a base, is known as saponification because it is used in the preparation of soap.

  • The molecules of soap normally are sodium or potassium salts of long-chain carboxylic acids.

  • Interestingly, the ionic-end of soap dissolves in water whereas the carbon chain dissolves in oil. This typical features of the soap molecules forms structures known as micelles (see the image given below)

  • In micelles, one end of the molecules is towards the oil droplet whereas the ionic-end remains outside.

  • The soap micelle helps in dissolving the dirt in water; likewise, the clothes get cleaned.

  • On the other hand, detergents are usually ammonium or sulphonate salts of long chain carboxylic acids, which remain effective even in hard water.

  • Detergents are customarily used to make shampoos and some other products for cleaning clothes.