Unhybridized p orbital energy

[TrishaP_3E]

In Lecture today (11/23) Dr. Lavelle talked about Ethene, and unhybridized p orbitals, and hybridized p orbitals, and the energy difference between the two. Can someone explain why this is significant as I am a little confused about what he said.

[Janelle Gokim 3B]

The energy difference between the hybridized orbital and the unhybridized orbital explains why there isn't spin paired electrons. In the example, because the 2sp^2 hybridized orbital is closer in energy to the 2p orbital than the 2s is in that respect, there is going to be more electron repulsion, so rather than having the electrons spin paired, it will actually occupy the unhybridized 2p orbital. This is how the pi bond comes into play, and explains the formation of a double bond in ethene. If the electron were to instead pair with one of the others in the hydridized orbitals, we would have an entirely different shape that wouldn't match up with the trigonal planar formation found around each C in ethene.

[Isaac Wen]

The energy difference between the hybridized orbital and the unhybridized orbital explains why there isn't spin paired electrons. In the example, because the 2sp^2 hybridized orbital is closer in energy to the 2p orbital than the 2s is in that respect, there is going to be more electron repulsion, so rather than having the electrons spin paired, it will actually occupy the unhybridized 2p orbital. This is how the pi bond comes into play, and explains the formation of a double bond in ethene. If the electron were to instead pair with one of the others in the hydridized orbitals, we would have an entirely different shape that wouldn't match up with the trigonal planar formation found around each C in ethene.

Just as a follow-up question, is 2sp^2 closer in energy to the 2p orbital because it "consists" of more p orbitals (2) than s orbitals (1)?

[Lorraine Jiang 2C]

Hi! I think you can think of hybridized orbitals a combination of s and p orbitals, and for 2sp^2 orbitals, it is closer towards the 2p orbital because it has slightly higher energy. And because of this, we will not have a paired electron spin at the 2sp^2 but a single electron at the 2p orbital because of electron repulsion.

Hope it helps!

[Janelle Gokim 3B]

The energy difference between the hybridized orbital and the unhybridized orbital explains why there isn't spin paired electrons. In the example, because the 2sp^2 hybridized orbital is closer in energy to the 2p orbital than the 2s is in that respect, there is going to be more electron repulsion, so rather than having the electrons spin paired, it will actually occupy the unhybridized 2p orbital. This is how the pi bond comes into play, and explains the formation of a double bond in ethene. If the electron were to instead pair with one of the others in the hydridized orbitals, we would have an entirely different shape that wouldn't match up with the trigonal planar formation found around each C in ethene.

Just as a follow-up question, is 2sp^2 closer in energy to the 2p orbital because it "consists" of more p orbitals (2) than s orbitals (1)?

I'm not exactly sure but I would assume so yes.