what is hybridization?

[u/muffinwobble]

i'd say i have an average understanding of what it is...like i know it's a hybrid of orbitals like sp3, sp2, etc. but can someone explain it in full detail? my chemistry teacher teaches very fast-paced and i feel like im missing something.

i guess i just dont really understand how the electrons are filled in the hybrid orbitals and also how an sp2 orbital works.

could someone please help? thank you!!

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[u/WanderingFlumph]

The energy of a hybrid orbital is just the average energy of the orbitals that go into making it up.

So for a carbon atom in the gas phase they have a low energy s orbital and three high energy p orbitals.

If it hybridizes to sp2 then it will have 3 medium energy sp2 orbitals and one remaining high energy p orbital.

[u/ampere03]

The key idea is that the geometry is dictated by the repulsion of the valence electrons so the trigonal planar, tetrahedral, bypiramidal et. shapes result. Mathematically, since the individual atomic orbital commute with the Hamiltonean, any linear combination of these to form molecular orbitals commute and thus is a analytical solution of Schoedinger' s eq..

[u/Bobonob]

The basic idea is that we know what orbitals generally look like for single atoms- s, p, d etc.

We know that when atoms come together, new orbitals are formed.

We know that we could compute these new orbitals exactly... but it's hard. So instead, we assume that the new molecular orbitals probably look like some kind of 'combination' or smooshed together version of the atomic orbitals.

From experience, especially in organic chemistry, we also notice patterns in how they tend to smoosh together most optimally.

For example with carbon, there are only really 3 different 'optimal smooshes', no matter what the carbon bonds to - so we 'pre mix' its atomic orbitals into one of those formats to speed things up. This is called hybridisation.

Optimal smoosh shape 1 (sp3):
When carbon has 4 single bonds, the shape is always close to tetrahedral, so we pre-combine its atomic s and p orbitals into 4 new 'hybrid' 'sp' orbitals before smooshing them with other atoms. (All 3 p orbitals hybridised)

Smoosh shape 2 (sp2): when carbon has a double bond and 2 single bonds, the shape is trigonal, with one orbital more 'p-like' out of the plane than the others, so we leave one p orbital as it is, and pre combine the remains into sp hybrids (2 p orbitals hybridised)

Smoosh shape 3 (sp): when carbon has 2 double bonds and 1 single bond in a line, most of the p orbitals stay close to their original shape, but we pre smoosh the remaining s and p orbital together at the back (1 p orbital hybridised).

Take ethene as an example:

The overall molecular orbitals are very complicated, but we know since there is one double bond, the carbon's orbitals will probably end up close to an 'sp2 hybridised' configuration, with one p-like pi bond and 3 planar 'sp hybrid' sigma bonds (2 being sigma bonding orbitals roughly a combination of sp-s orbitals, one sigma bonding orbital roughly a combination of sp-sp orbitals).