Carbon and Its Compounds

Catenation The property of self linking of carbon atoms through covalent bonds to form long chains or rings is called catenation.

• Other element which shows the catenation property is silicon.
  
• The bonds formed between the carbon and other elements are very strong because small size of

carbon enables the nucleus to hold on to shared-pair of electron strongly.

Versatile nature of carbon

1. Catenation – self linking of carbon atoms to form long chains or rings.
   
2. Tetravalency –sharing of 4 electrons with other atoms of carbon or any other monovalent element.
   

Saturated Carbon Compounds Compounds of carbon which have only single bonds between the carbon atoms are called saturated carbon compounds.

E.g. methane, ethane, etc.

Unsaturated carbon compounds Compounds of carbon which have double or triple bonds between the carbon atoms are called unsaturated carbon compounds.

E.g. ethene, ethyne, etc.

Straight chain compounds Carbon compounds in which no carbon atom of the chain is linked to more than two other carbon atoms are called straight chain compounds.

E.g. methane, ethane, propane, etc.

Branched chain compounds Carbon compounds, in which at least one carbon atom of the chain is linked to three or four other carbon atoms are called branched chain compounds. E.g. 2-methylpropane.

Cyclic compounds Carbon compounds in which carbon atoms are arranged in a ring are called cyclic compounds. These are of two types –

1. Saturated cyclic compounds. E.g. cyclopropane, cyclobutane, cyclopentane, etc.
   
2. Unsaturated cyclic compounds. E.g. benzene.
   Hydrocarbons. The carbon compounds which contain only hydrogen and carbon are called

Hydrocarbons

• Hydrocarbons which contain only single bonds between the carbon atoms are called alkanes. Their general formula is C_nH_2n+2.
  
• Hydrocarbons which contain one or more double bonds between the carbon atoms are called alkenes. Their general formula is CnH2n.
  
• Hydrocarbons which contain one or more triple bonds between the carbon atoms are called alkynes. Their general formula is C_nH_2n-2.
  

Functional group An atom or group of atoms present in a molecule which determines its functions or chemical properties is called a functional group. It is the most reactive site of a carbon compound.

Homologous series The family of organic compounds having same functional group, similar chemical properties and the successive members of which differ by CH₂ group is called a homologous series.

Characteristics of a homologous series

1. All the members can be represented by same general formula.
   
2. The molecular formulae of two successive members differ by CH₂ group or by 14u.
   
3. All the members have same functional group.
   
4. All the members show similar chemical properties.
   

• The melting and boiling points of the members of homologous series increase gradually because their molecular masses increase.