Hybridisation is the concept of mixing orbitals to form new hybrid orbitals which would allow different orientations to take place in order to be able to produce the greatest possible angles between different bonds.
An atom that can be used to show different types of hybridisation is C since this can produce three different hybrid orbitals, mainly sp3, sp2 and sp.
The ground state of C is: The excited state of C is:
In an sp3 hybridisation the four orbitals would then recombine to form 4 new hybrid orbitals, which can then rearrange to form a tetrahedron. this can be seen as follows:
In an sp2 only three orbitals are hybridised while the last p orbital would remain unchanged, producing a planar compound with a perpendicular orbital. This can be seen as follows:
In an sp hybridised orbital the hybridisation occurs only between an s orbital and one of the 3 p orbitals producing two sp hybrid orbitals and leaving two p orbitals. This can be seen as follows:
