[orgo814]

What's the best way to explain hybridization to freshmen level students? It seems to be a hard subject to explain to novices.

[phth]

The way I think about bowdlerizing the information is explaining it as the addition of wavefunctions because that is all it really is.  Breaking it down to constructive and destructive intereference patterns is all it really is which also makes it easy to understand that hybridization is not a change in energy, but rather the coalescence of 4 waves (sp3)-->3 additions when you take one out(sp2, different oxidation state) etc.  You can demonstrate with a volunteer and a string adding an extra shake vs not

[Enthalpy]

The authentic wavefunctions contain an exp(2iπEt/h), where E differs between 2s and 2p, even if by little.
Linear combinations of these solutions still satisfy Schrödinger's equation by linearity but they are not stationary because the E differ - so this is not the explanation. With this operation, you obtain the non-stationary solutions when the electron radiates as it changes its orbital.

The good explanation must be seriously more complicated, and probably needs a second atom, with perturbation theory and so on.

The original paper about hybridization could be clearer than what has been written later - it's often the case.

[Irlanur]

Linear combinations of these solutions still satisfy Schrödinger's equation by linearity but they are not stationary because the E differ

except for Hydrogen-(like atoms), atomic orbitals are NEVER a true solution of the SDE. They can't be. The Hamiltonian contains terms which up to two electron coordinates. An orbital, by definition, only contains one electron coordinate.

I would put it like that:

-For an exact treatment, we would need to solve the Schrödinger Equation with the molecular Hamiltonian.
-We can't find an analytical solution.
-For very small Molecules, there are very exact numerical solutions (not analytical doesn't mean not exact!)
-For every Molecule that Organic Chemists are interested in, we would need sophisticated and computer intensive algorithms. Even today, these results don't necessarily give exact solutions.
-We CAN get an intuitive understanding with qualitative MO-Theory (and or Valence Bond, however I still don't see the qualitative difference between them...)
-For that, we build the Molecular Orbitals from Atomic Orbitals (LCAO)
-If we have a saturated carbon atom, we could, in prinicple, use the atomic s and p orbitals, it's just very inconvenient. That's why we combine them BEFORE we actually build combinations with other atomic orbitals in the Molecule. That's all there is to Hybridisation. It's nothing spooky.

The original paper about hybridization could be clearer than what has been written later - it's often the case.

Do you know "the" original paper? The term definitely seems to be historically overused.