sp³ hybridization

Now let's see how hydridisation can account for each of these features, working towards methane then other alkanes:

Promote an electron from 2s to 2p to create an excited state... with 4 unpaired electrons we can form 4 bonds these bonds would be from 1 x C2s-H1s interaction and 3 x C2p-H1s interactions but these bonds will have different lengths and strengths the 3 C-H bonds from the p orbitals maybe expected to have H-C-H bond angles of 90 degrees
"Blend" (i.e. hybridise) the s and the three p orbitals... since we "mixed" 4 orbitals, we get a set of 4 sp3 orbitals each sp3 hybrid contains a single unpaired electron
	The sp3 hybrid orbital looks like a "distorted" p orbital with unequal lobes. The 4 sp3 hybrids point towards the corners of a tetrahedron.

For methane: 4 equivalent C-H s bonds can be made by the interactions of Csp3 with a H1s
Now ethane, H3C-CH3 as a model for alkanes in general: Both C are sp3 hybridised. 6 C-H s bonds are made by the interaction of C sp3 with H1s orbitals (see the red arrows) 1 C-C s bond is made by the interaction of C sp3 with another C sp3 orbital (see the green arrow)

Summary

• sp³occurs when a C has 4 attached groups
• sp³ has 25% s and 75% p character
• the 4 sp³ hybrids point towards the corners of a tetrahedron at 109.5^o to each other
• each sp³hybrid is involved in a s bond