What is maximum Pauling electronegativity or energy difference between orbitals?

[adf89812]

TL;DR Summary

AO energy difference maximum such that bonding orbital is still possible is what?

>-Atomic orbitals must be at the similar energy levels to combine as molecular orbitals, said Wikipedia.


This is unclear. How do you quantify how "similar" means?

I heard electronegative is tied to atomic radius is tied to atomic orbital energy.


What are two atoms that would in theory form an ionic compound if you use a naive theory but actually don't because the atomic orbitals are too dissimilar in energy levels according to molecular orbital theory?

>The essential point of Pauling electronegativity is that there is an underlying, quite accurate, semi-empirical formula for dissociation energies, namely:
>$$
E_{\mathrm{d}}(\mathrm{AB})=\frac{E_{\mathrm{d}}(\mathrm{AA})+E_{\mathrm{d}}(\mathrm{BB})}{2}+\left(\chi_{\mathrm{A}}-\chi_{\mathrm{B}}\right)^2 \mathrm{eV}
$$

According to this equation, you have a stronger bond when the atomic orbital energy difference $$(\chi_A-\chi_B)$$ is high. Does this equation contradict the first quote?

 

[Borek]

There is no strict definition of what "similar" means, these are just rules of thumb, so they use lots of handwaving.

>$$
E_{\mathrm{d}}(\mathrm{AB})=\frac{E_{\mathrm{d}}(\mathrm{AA})+E_{\mathrm{d}}(\mathrm{BB})}{2}+\left(\chi_{\mathrm{A}}-\chi_{\mathrm{B}}\right)^2 \mathrm{eV}
$$

According to this equation, you have a stronger bond when the atomic orbital energy difference $$(\chi_A-\chi_B)$$ is high. Does this equation contradict the first quote?

Only if you ignore first part of the formula. You can have very strong bond even if $$(\chi_A-\chi_B)$$ is zero.

 

[adf89812]

There is no strict definition of what "similar" means, these are just rules of thumb, so they use lots of handwaving.


Only if you ignore first part of the formula. You can have very strong bond even if $$(\chi_A-\chi_B)$$ is zero.

what's the non-handwaving answer they're avoiding?

 

[Borek]

That there is no such thing like ionic/molecular bond and that the full and exact answer is just a direct application of quantum mechanics (and as such far from being easily applicable).