hybrid orbitals out of which two contain one electron each and the other two contain a pair of electrons. These four sp hybrid orbitals acquire a tetrahedral geometry, with two corners occupied by hydrogen atoms while the other two by the lone pairs. The bond angle in this case is reduced to . ° from .
° (Fig. . ) and the molecule thus acquires a V-shape or angular geometry. Fig.
. Formation of H O molecule . . Other Examples of sp , sp and sp Hybridisation sp Hybridisation in C H molecule: In ethane molecule both the carbon atoms assume sp hybrid state.
One of the four sp hybrid orbitals of carbon atom overlaps axially with similar orbitals of other atom to form sp - sp sigma bond while the other three hybrid orbitals of each carbon atom are used in forming sp – s sigma bonds with hydrogen atoms as discussed in section . . (iii). Therefore in ethane C–C bond length is pm and each C–H bond length is pm.
sp Hybridisation in C H : In the formation of ethene molecule, one of the sp hybrid orbitals of carbon atom overlaps axially with sp hybridised orbital of another carbon atom to form C–C sigma bond. While the other two sp hybrid orbitals of each carbon atom are used for making sp – s sigma bond with two hydrogen atoms. The unhybridised orbital ( p x or p y ) of one carbon atom overlaps sidewise with the similar orbital of the other carbon atom to form weak π bond, which consists of two equal electron clouds distributed above and below the plane of carbon and hydrogen atoms. Thus, in ethene molecule, the carbon- carbon bond consists of one sp – sp sigma bond and one pi ( π ) bond between p orbitals which are not used in the hybridisation and are perpendicular to the plane of molecule; the bond length pm.