Hydrocarbons

Hydrocarbons: All carbon compounds which contain just carbon and hydrogen are called hydrocarbons.

Formulae of organic compounds:

(i) General formula: General formula represents a function for n numbers of each atom in a molecule. 

Example: for alkane: C_nH_2n+2

(ii) Molecular formula: Molecular formula represents actual number of atoms of a molecule. 

Example: For Ethane: C₂H₆

(iii) Condensed formula: Condensed formula represents group of atoms linked together to each carbon atom. 

Example: For Ethane: CH₃CH₃

(iv) Structural formula: It represents exact arrangement of atom of a molecule. 

Example: For Ethane: 

(v) Electronic formula: Electronic formula represents the sharing of electrons amongs atoms of a molecules. 

Example: For Ethane: 

Saturated Carbon Compounds: 

Compounds of carbon, which are linked by only single bonds between the carbon atoms are called saturated compounds.

Example: Alkanes like methane, Ethane, propane butane etc.

General formula for Alkanes: C_nH_2n+2

Using formula for Methane;

C_nH_2n+2

Putting n =1 we get

C₁H_{2x1 + 2}

CH₄

Similarily; 

For Ethane:

Putting n =2 we get

C₂H_{2x2 + 2}

C₂H₆

Similarily we can find molecular formula for propane, butane, pentane and so on ....... 

Alkanes: The saturated hydrocarbons in which carbon atom linked together with single bond are called alkenes.

Structure of Methane (single bond);

Single carbon atom has four unsatisfied valency Linked with Hydrogen atom like figure. 

Electrone Dot strucuture of Methane

Structure of Ethane (single bond);

  C - C [ carbon atoms linked together witha single bond] 

Next Linked with Hydrogen atom to carbon unsatisfied valency like given figure;  

Electron Dot structure of Ethane 

Structure of propane (single bond);

Structure of Butane (single bond);

Structure of pentane (single bond);

Structure of hexane (single bond);

Unsaturated Carbon Compounds: 

Compounds of carbon having double or triple bonds between their carbon atoms are called unsaturated compounds.

Example: Alkenes like and Alkynes;

Structure of alkenes (Double bond);

General Formula for Alkenes: C_nH_2n

The simplest Alkenes is Ethene;

So Ethene has 2 carbon atoms; 

Now putting n = 2 in general formula;

C₂H_2x2 = C₂H₄

Propene has 3 carbon atoms;

Now putting n = 3 in general formula;

 C₃H_2x3 = C₃H₆

Similarily we can find the molecular formula for other Alkenes like butene, pentene and hexene etc.

Alkenes: The unsaturated hydrocarbons which contain one or
more double bonds are called alkenes.

Structural Formula of Alkene: 

Name of Alkenes	Molecular Formula	Structural Formula
Ethene	C2H4
Propene	C3H6
Butene	C4H8
Pentene	C5H10
Hexene	C6H12
Heptene	C7H14
Octene	C8H16
Nonene	C9H18
Decene	C10H20	​

Electron Dot Sructure of Ethene: 

              Ethene (C₂H₄)

Electron Dot Sructure of Propene: 

                        Prooene (C₂H₄)

Similarily We can draw electron dot structure of other Akenes; 

Structure of Alkynes (Triple Bond):

General formula of Alkynes: C_nH_2n-2

The simplest alkynes is Ethyne;

Ethyne has two carbon atoms. Hence, Using the formula;

Putting n = 2 for Ethyne,

C₂H_2x2-2 = C₂H₂

  ∴ Ethyne = C₂H₂

Similarily we can find Propyne; 

Putting n=3 for Propyne; 

C₃H_2x3-2 = C₃H₄

  ∴ Propyne = C₃H₄

Alkynes: 

Long chain formula is abbreviated as bellow;

[Nonyne] CH≡CCH₂CH₂CH₂CH₂CH₂CH₂CH₃ can be written as  

CH≡C (CH₂)₆CH₃

similarily;

[Decyne] CH≡CCH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₃ can be written as 

CH≡C (CH₂)₇CH₃

Defferences between saturated and unsaturated carbon compound: