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: CnH2n+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: CnH2n+2
Using formula for Methane;
CnH2n+2
Putting n =1 we get
C1H2x1 + 2
CH4
Similarily;
For Ethane:
Putting n =2 we get
C2H2x2 + 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.
Name of Alkanes | Molecular Formula | Condensed structural Formula |
Methane | CH4 | CH4 |
Ethane | C2H6 | CH3CH3 |
Propane | C3H8 | CH3CH2CH3 |
Butane | C4H10 | CH3CH2CH2CH3 |
Pentane | C5H12 | CH3CH2CH2CH2CH3 |
Hexane | C6H14 | CH3CH2CH2CH2CH2CH3 |
Heptane | C7H16 | CH3CH2CH2CH2CH2CH2CH3 |
Octane | C8H18 | CH3CH2CH2CH2CH2CH2CH2CH3 |
Nonane | C9H20 | CH3CH2CH2CH2CH2CH2CH2CH2CH3 |
Decane | C10H22 | CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3 |
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: CnH2n
The simplest Alkenes is Ethene;
So Ethene has 2 carbon atoms;
Now putting n = 2 in general formula;
C2H2x2 = C2H4
Propene has 3 carbon atoms;
Now putting n = 3 in general formula;
C3H2x3 = 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.
Name of Alkenes | Molecular Formula | Condensed structural Formula |
Ethene | C2H4 | CH2=CH2 |
Propene | C3H6 | CH3CH=CH2 |
Butene | C4H8 | CH3CH2CH=CH2 |
Pentene | C5H10 | CH3CH2CH2CH=CH2 |
Hexene | C6H12 | CH3CH2CH2CH2CH=CH2 |
Heptene | C7H14 | CH3CH2CH2CH2CH2CH=CH2 |
Octene | C8H16 | CH3CH2CH2CH2CH2CH2CH=CH2 |
Nonene | C9H18 | CH3CH2CH2CH2CH2CH2CH2CH=CH2 |
Decene | C10H20 | CH3CH2CH2CH2CH2CH2CH2CH2CH=CH2 |
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: CnH2n-2
The simplest alkynes is Ethyne;
Ethyne has two carbon atoms. Hence, Using the formula;
Putting n = 2 for Ethyne,
C2H2x2-2 = C2H2
∴ Ethyne = C2H2
Similarily we can find Propyne;
Putting n=3 for Propyne;
C3H2x3-2 = C3H4
∴ Propyne = C3H4
Alkynes:
Name of Alkenes | Molecular Formula | Condensed structural Formula |
Ethyne | C2H2 | CH≡CH |
Propyne | C3H4 | CH≡CCH3 |
1-Butyne | C4H6 | CH≡CCH2CH3 |
1-Pentyne | C5H8 | CH≡CCH2CH2CH3 |
1-Hexyne | C6H10 | CH≡CCH2CH2CH2CH3 |
1-Heptyne | C7H12 | CH≡CCH2CH2CH2CH2CH3 |
1-Octyne | C8H14 | CH≡CCH2CH2CH2CH2CH2CH3 |
1-Nonyne | C9H16 | CH≡CCH2CH2CH2CH2CH2CH2CH3 |
1-Decyne | C10H18 | CH≡CCH2CH2CH2CH2CH2CH2CH2CH3 |
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:
Saturated Compound | Unsaturated Compound |
1. It has single bond between carbon atoms. 2. There occurs substitution reaction in it. 3. Example: Alkanes. 4. They are less reactive than the unsaturated carbon compound. |
1. It has double and triple bond between carbon atoms. 2. There occurs addition reaction in it. 3. Example: Alkenes, Alkynes. 4. They are more reactive than the saturated carbon compounds. |