Page 46 - 11-chem-6

6 CHEMICAL BONDING eLearn.Punjab

The e nergies of hybrid orbitals are lower than unhybridized orbitals. Following diagram Fig.
(6.10) shows,
howoutermostfouratomicorbitalsofcarbonmixuptogivefourhybridorbitalsofequalenergyandshape.
hen 90°.
The four new hybrid orbitals of equal energy have a tetrahedral geometry with carbon at
the centre. The four equivalent hybrid orbitals are directed towards the four corners of a regular
tetrahedron. Each sp3 hybrid orbital consists of two lobes, one larger and the other smaller. For the

Fig (6.10) sp3 hybridization of carbon atom
to give four sp3-hybrid orbitals

sake of simplicity, the small lobe is usually not shown while representing sp3 hybrid orbitals.

The hybrid orbitals are oriented in space in
such a manner that the angle between them
is 109.5° as shown in Fig(6.11a,b). Methane
molecule is formed by the overlap of sp3
hybrid orbitals of carbon with 1s orbitals of
four hydrogen atoms separately to form four
sigma bonds. The molecule, thus formed,
possesses a tetrahedral geometry. The four
C-H bonds which result from sp3 -s overlaps
are directed towards the corners of a regular Fig(6.11) Four sp3-s overlaps in tetrahedral structure of CH4 molecule.
tetrahedron. There are six bond angles each
109.5°. The tetrahedral structure of CH4 has four faces, four corners and six edges.

46