Thursday, July 11, 2013

Valence

Valence and Hybridization :
                   The electronic configuration of carbon indicates its valence should be 2 ; but
 actually it is 4.How is it happen ? It is explained lucidly in the following animation. Also the
 formation of sigma- and pie-covalent bonds by overlapping of atomic orbitals and hybrid
orbitals are shown in the video.
                  In ground state the carbon atom has 2 unpaired electrons, so it should have
valence 2. But on taking 96 kcal/mol energy, one of the 2s-electrons excited to 2p-energy
state prior to bond formation. This energy is compensated by the energy evolved by the
 formation of four covalent bonds (about 100x4= 400 kcal/mol). As the resultant four bonds
are equivalent, the one 2s and the three 2p orbitals of carbon atom hybridizes to yield four
equivalent sp^3 orbitals.



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