Hybridization of Carbon: A Detailed Explanation with Examples, Lecture notes of Chemistry

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sp 2 sp 2 d sp 2 sp 2 p z p z p p

Hybridization

Hybridization of Carbon

A typical C-H has a bond strength of 100 Kcal/mol Net-Energy change = (400-97) Kcal/mol = 300 Kcal/mol In the excited state carbon has four unpaired electrons and can form four bonds with hydrogen.

Methane - sp

3

Hybridized

What is the nature of the four C-H bonds in methane? Since excited carbon uses two kinds of orbitals ( 2 s and 2 p) for bonding purpose, we might expect methane to have two kinds of C-H bonds. In fact this is not the case. A large amount of evidence show that all four C-H bonds in methane are identical in terms of their length and strength.

Each bond in CH 4 is formed by overlap of an sp 3 hybrid orbital of carbon with a 1 s orbital of hydrogen. These four bonds point to the corners of a tetrahedron. **H H H H C . . . .

109 0 A 0 Bond strength = 104 Kcal/mol**

The tetrahedral shape of an sp 3 hybridized carbon

Ethane (C 2

H

6 ) – sp 3 Hybridization C C H H H H H H We can picture the ethane molecule by assuming that the two carbon atoms bond to each other by sigma overlap of an sp 3 hybrid orbital from each carbon.

**C C H H H H H H 109 0 109 0

0 A 0 A Structure of Ethane**

Ethylene (C

2

H

4

)-sp

2

Hybridization

H

H H

H

sp

2

hybridization of a carbon

ground state excited state sp 2 hybridized state 2p z sp 2 2s 2p 2s 2p unhybridized p orbital

sp 2 sp 2 d sp 2 sp 2 p z pz p p d Bond are formed by end-on overlap of two sp 2 hybrid orbitals. p bond are formed by side-by-side overlap of two 2 p orbitals. The electron density in a p bond is farther from the two nuclei, p bonds are usually weaker and therefore more easily broken than d bonds.

Planar shape

trans = The substituents are on opposite side of the double bond. cis = The substituents are on the same side of the double bond.

Examples C C H Cl Cl H C C Cl Cl H H cis - 1,2-dichloroethene trans - 1,2-dichloroethene