Please explain hybridisation in alkanes,alkenes and alkynes.

Asked by Benjamin | 6th Sep, 2015, 05:47: PM

Expert Answer:

Alkanes have sp3 hybridisation as follows:
  • The electronic configuration of carbon in the ground state is 2s22px12py1
  • Carbon form four bonds by promoting one of the 2s electrons to 2pz orbital.
  • Hence, the electronic configuration of carbon in the excited state is 2s12px12py12pz1.
  • These singly occupied four orbitals hybridise to form four sp3 hybrid orbitals.
  • They have 109º angle between each of the two sp3 bonds.
  • The geometry is tetrahedral.
Hybridisation in alkanes, alkenes and alkynes is as follows:
 

 

Alkyne

Alkene

Alkane

Hybridisation of carbon to which H atom is attached

sp

sp2

sp3

Percentage s character of carbon

50%

(maximum)

66.6%

25%

(minimum)

Electronegativity of carbon atom

Highest

Less than alkyne and more than alkane

Lowest

Extent of attraction of hydrogen atoms of C-H bonds towards C

Highest 

Less than alkyne and more than alkane

Lowest

Ease of liberation of H atoms as protons

Highest

Less than alkyne and more than alkane

Lowest

Acidic character

Highest

Less than alkyne and more than alkane

Lowest

Answered by Prachi Sawant | 7th Sep, 2015, 10:14: AM