Hybridization in molecules

The justification we gave for invoking hybridization in molecules such as BeH2, BF3 and CH4 was that the bonds in each are geometrically and chemically equivalent, whereas the atomic s- and p-orbitals on the central atoms are not. By combining these into new orbitals of sp, sp2 and sp3 types we obtain the required number of completely equivalent orbitals. This seemed easy enough to do on paper we just drew little boxes and wrote sp2 or whatever below them. But what is really going on here ... 

HYBRIDIZATION IN MOLECULES CONTAINING DOUBLE AND TRIPLE BONDS... 

The following rnle helps ns predict hybridization in molecules containing mnlti-ple bonds If the central atom forms a donble bond, it is. sp. iiybridized if it forms two donble bonds or a triple bond, it is. sp-hybridized. Note that this rule applies only to... 

From Eq. (4.7), we can deduce that a C—C bond vibrates at a lower wavenumber than a C=C bond, because the force constant for the C—C bond is smaller than that for C=C. For example, C—C vibrates at 1200 cm and C=C vibrates at 1650 cm . In general, force constants for bending vibrations are lower than stretching vibrations. Resonance and hybridization in molecules also affect the force constant for a given bond. 

Hybridization in Molecules Containing Double and Triple Bonds... 

---