When Do Orbitals Hybridize in Chemistry?

[cosmonova]

Hello,

The geometric form of the water molecule is explained in chemistry books by the hybridization of certain orbitals, in this case the 2p and 2s orbitals.The resulting hybridized orbital then gets the geometric form observed.

I know that hybridization is permitted by the fact that Shrodinger's equation is linear.But what I don't understand is "when" orbitals hybridize and when don't they?

Do orbitals in isolated atoms hybridize ?Or is hybridization a phenomenon only occurring when two or more atoms approach each other?

I personnaly understand by hybridization the interference of the wave functions of two or more electrons.Is this correct?

Thank you very much.

 

[nbo10]

What would happen if the energy difference of the orbitals is large; what would happen is the difference is small??

JMD

 

[marlon]

Generally hybridization between two orbitals occurs when the separation between their energylevels is "not too big". They form a bound state because the potential energy of the joint state is lower then that of the atoms or particles apart.

Basically hybridization-processes lower the total potential energy;which corresponds to a more stable situation. Thats's the mean reason for hybridization. One describes this using the fact that superpositions of the schrodinger equation are still valid solutions. This is the linearity

regards
marlon

 

[cosmonova]

energy of orbitals

Thank you guys for the replies.
Ok, orbitals hybridize because they form an orbital of less energy.
The next question is , how can I calculate the energy of an orbital knowing its geometric form and maybe other information about it?

And by the way, are orbitals' phases also quantized?

 

[marlon]

the fase of an electronwavefunction (remember that an orbital is a representation of a wavefunction) can be quantized . This happens for example when magnetic monopoles are taken into account in the EM. The consequance is that the product of the electric and magnetic coupling constants is constant.

To calculate these energies one has to perform QM and perturbationtheory in order to fully describe the interactions of electrons and nucleons apart and between each other...

 

[cosmonova]

I have had a little knowledge of QM.
Could you please explain more to me how I could calculate the energy of an orbital and what is the relation between the energy of an orbital and its geometric form?

Thanks again

 

[marlon]

orbitals are just the sferical harmonics, which are the angular parts (depending on the polar-theta and azymuthal-phi) of the wavefunction that is the solution of the Schrodinger equation. these parts are merely the eigenfunctions of the L² and L_z operators (angular momentum, right).L² as an operator working on the sferical harmonics Y(tehta,phi) gives rise to the eigenvalues h²l(l+1) with l the orbital quantumnumber. L_z has eigenvalues mh. h is the Planckconstant devided by 2pi. Grouptheory shows us that (L²)>(L_z) so that l(l+1)>m². This means that for each l we have the following m values : -l,...0,...l

These sferical harmonics describe fully the different possible energylevels because H, L² and L_z all commute so that their mutual eigenvectors (the sferical harmonics) form a complete othogonal set and diagonalize the H representation matrix. So an energy level is denoted by l and has 2l+1 possible sub-energylevels that can be shown experimantally by the Zeemaneffect for magnetic fields or the Starcheffect for external electric fields. So l=2 has five different orbitals each corresponding to the 5 possible m values. The very well known plots of these orbitals that we see in each textbook or not the actual form of the orbotals themselves. These figures have as equation the square of the sferical harmonics, which represent the probability one finds an electron (and thanks to Pauli maximal two elektrons) in the orbital.

regards
marlon

 

[thedy]

I have read this thread,and I don t understand one thing.
When I know,the molecules have non-hybridized or hybridized orbitals?
For example in H20.There is sp3 orbital,but why?Is it necessary?Why cannot it be easy:Oxygen has electron configuration:2s 2px 2py 2pz.2px and 2py are going to join with 1s orbital of Hydrogen?Why is it not so?And in other similar examples?
Thanks

 

[DrDu]

In fact, in H2O the bonding is better described using only the p orbitals than sp3 hybrid orbitals. The optimal hybridization is determined by maximization of the overlap with the hydrogens (and minimization with the other hydrogen, respectively) and the energy difference of the s and the p orbitals. In O, this energy is very high so that hybridization is unfavorable.

 

[juanrga]

Hello,

The geometric form of the water molecule is explained in chemistry books by the hybridization of certain orbitals, in this case the 2p and 2s orbitals.The resulting hybridized orbital then gets the geometric form observed.

The geometric form of the water molecule is not explained by hybridization in chemistry books dealing with molecular orbital (MO) theory. Hybridization belongs to the old Valence bond (VB) theory.

Moreover, VB theory does not really explains the geometry, but obtains it because of lucky self-canceling deviations. Check

http://en.wikipedia.org/wiki/Orbital_hybridisation#Explanation_of_the_shape_of_water