# What are the shapes of molecular orbitals?

## Main Question or Discussion Point

Please, can someone answer my question? I know the shape of sp hybrid orbital, but want to know about the others ( sp2,sp3,dsp2,dsp3,d2sp3,d3sp3 ). And are there any other type of molecular orbitals?

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Gokul43201
Staff Emeritus
Gold Member
Okay, an sp hybrid orbital looks pretty much like one of the p-orbitals. It has 2 lobes directed at 180 deg from each other. The other hybrid orbitals too take on shapes that reflect the symmetry of the hybridisation.

sp2 orbitals have 3 such lobes pointing out towards the vertices of an equilateral triangle centered on the nucleus.

sp3 orbitals have 4 lobes pointing out towards the vertices of a regular tetrahedron centered on the nucleus.

dsp2 orbitals have 4 lobes pointing out towards the vertices of a square centered on the nucleus.

dsp3 orbitals have 3 lobes pointing out towards the vertices of an equilateral triangle centered on the nucleus and the other 2 pointing normal to this plane, one upwards and one downwards.

d2sp3 orbitals have 4 lobes pointing out towards the vertices of a square centered on the nucleus and the other 2 pointing normal to this plane, one upwards and one downwards.

I've never come across a d3sp3 orbital, but if that were to exist, I would imagine that it would have have 5 lobes pointing out towards the vertices of a regular pentagon centered on the nucleus and the other 2 pointing normal to this plane, one upwards and one downwards. (I wouldn't extend this beyond 5 though; the in-plane angle will become significantly smaller than the out of plane angle, and that wouldn't be very stable).

Oh, and by the way, none of these are molecular orbitals. They are all hybridized ATOMIC orbitals.

You can see (and construct) such orbitals with the program "Atom in a Box" (macintosh only).
Some examples are on the web page:
http://daugerresearch.com/orbitals/

Gokul43201 said:
I've never come across a d3sp3 orbital, but if that were to exist, I would imagine that it would have have 5 lobes pointing out towards the vertices of a regular pentagon centered on the nucleus and the other 2 pointing normal to this plane, one upwards and one downwards. (I wouldn't extend this beyond 5 though; the in-plane angle will become significantly smaller than the out of plane angle, and that wouldn't be very stable).
Well, thanks for everything, but u know d3sp3 does exist. Examples are PCl5, PF5, SbCl5. By the way, yes, your imagination is correct. I found out its shape. It's what you described. Thanks.

So, what are molecular orbitals then?

Neha Sanghvi said:
Well, thanks for everything, but u know d3sp3 does exist. Examples are PCl5, PF5, SbCl5. By the way, yes, your imagination is correct. I found out its shape. It's what you described. Thanks.
So, what are molecular orbitals then?
Atomic orbital is the orbital of electron in an atom.

Molecular orbital is the orbital of electron in a molecule.

Orbitals that you wrote form molecular orbitals (in the approximation of EV). In the approximation of OM, molecular orbitals are completely different and there is not any thing like sp3 etc.

Your orbitals are valid for semiempirical questions and, in chemistry, only used in basic courses of organic or inorganic chemistry.

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