Hybridization Question

[MissionStanford]

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If we need to form 5 bonds, we gets sp3d hybridization. Let's say we are hybridizing 3s, 3p and 3d to do this. Why don't we do this with 4s instead of 3d to essentially get "sp3s" hybridization? After all, 4s is lower in energy than 3d and filled before 3d.

 

[MissionStanford]

Just realized I posted this in MCAT Discussions. Can someone move this to the Q&A section?

 

[MD Odyssey]

The real answer to this is that it is a lot more complicated. Hybridization isn't actually what's really going on, but it leads to the right answer. The MCAT really won't require you to go beyond what you've already gotten.

 

[gettheleadout]

If I had to guess, I would guess it's either because the hybridized orbitals must all be in the same principal energy level, or the fact that hybridizing two spherical orbitals, one of which is inside the other, isn't geometrically feasible for some reason.

But, as MD Odyssey said, this question is too advanced for the MCAT.

Moving to Q&A.

 

[Postictal Raiden]

If we need to form 5 bonds, we gets sp3d hybridization. Let's say we are hybridizing 3s, 3p and 3d to do this. Why don't we do this with 4s instead of 3d to essentially get "sp3s" hybridization? After all, 4s is lower in energy than 3d and filled before 3d.

I think 4s is higher in energy than 3d.

 

[gettheleadout]

I think 4s is higher in energy than 3d.

4s is lower according to the Aufbau Principle.

 

[ChemTutor]

If we need to form 5 bonds, we gets sp3d hybridization. Let's say we are hybridizing 3s, 3p and 3d to do this. Why don't we do this with 4s instead of 3d to essentially get "sp3s" hybridization? After all, 4s is lower in energy than 3d and filled before 3d.

if 4s are available, why do we use 3s for hybridization at all? 3p, 3d, 4s seems like the right choice using the outermost orbitals

 

[Postictal Raiden]

4s is lower according to the Aufbau Principle.

That's true. The fact that electrons from 4s are lost before ones from 3d (electrons are lost from the highest energy levels first) caused me to assume that 4s is higher in energy than 3d.