Methane hybridised orbitals

A carbon atom combining with four other atoms clearly does not use the one 2s and the three 2p atomic orbitals that would now be available, for this would lead to the formation of three directed bonds, mutually at right angles (with the three 2p orbitals), and one different, non-directed bond (with the spherical 2s orbital). Whereas in fact, the four C—H bonds in, for example, methane are known to be identical and symmetrically (tetrahedrally) disposed at an angle of 109° 28 to each other. This may be accounted for on the basis of redeploying the 2s and the three 2p atomic orbitals so as to yield four new (identical) orbitals, which are capable of forming stronger bonds (cf. p. 5). These new orbitals are known as sp3 hybrid atomic orbitals, and the process by which they are obtained as hybridisation ... 

This picture has the advantage over that in Fig. 1.12 that the C H bonds do have a direct relationship with the lines drawn on the conventional structure (Fig. 1.18b). The two descriptions of the overall wave function for methane lead to identical electron distributions hybridisation involves the same approximations, and the taking of s and p orbitals in various proportions and various combinations, as those used to arrive at Fig. 1.12. 

Ethane has a similar structure, each carbon being sp3 hybridised, there being a central link between the two carbon atoms by means of one sp3 orbital of one atom overlapping with the other. The three remaining sp3 hybrid orbitals on each carbon atom are used to overlap with three hydrogen Is orbitals. Both methane and ethane are typical saturated hydrocarbons, with the carbon exhibiting a full valency state of four. The bonds all result from end-on overlap between the orbitals, and are [Pg.39]

Fig. 1.11 Results of hybridisation of s and p atomic orbitals. Hybridisation In methane Is sp with four equivalent orbitals in a tetrahedral arrangement...

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