Atomic and Hybrid Orbitals

[Chiara Frank]

Hi! During lecture 19, Dr. Lavelle explained that hybrid orbitals are the average of atomic orbitals, however I still have some confusion about what this means. An example he used was Ethylene (C2H4). Since there are 3 regions of electron density, there are 3 hybrid orbitals. He used the electron configuration for Carbon to get the atomic orbitals, and wrote the 3 2p orbitals and the 1 2s orbital. However, I was confused about how he got the 1 2p orbital for the hybrid orbital, using the fact that the hybrid orbitals are the average of the atomic orbitals? I would greatly appreciate if anyone would be able to explain this. Thank you!

[Vance Liu]

Maybe since C is bonded to another C, the orbitals are not hybridized as they are with a H to C bond.

[Darren Apostol 2L]

In C2H4, the carbons assume sp2 hybridization which has 3 hybridized sp2 orbitals (e.g. hybridization of 2s, 2p^x, 2p^y) and 1 unhybridized p-orbital (2p^z). In terms of average, the unhybridized orbital isn't included.