# Hybridised orbitals

What determines which type of hybridisation (sp3/sp2/sp) a molecule will take? Methane/ethylene/acetylene all have the same electron configuration but undergo different different types of hybridisation- why?

• Why did I get voted down? O_o – user58953 Oct 10 '14 at 21:38

Methane $\ce{CH4}$, Ethylene $\ce{H2C=CH2}$ and acetylene $\ce{HC#CH}$ all have same electronic configuration but the number of unhybridised orbitals( and of course the hybridised orbitals) are different in each case due to formation of $\pi$ bonds.