[kapital]

I do not understand how orbital theory is compatible with resonance and inductive effect. For example, let consider anion F-CH2-CH2-COO-, due to inductive effect of fluorine the acid that forms this anion is a little bit more acidic than propionic acid. Now that could be interpreted as a negative charge distributed trough more atoms. Now what I do not know,is how would that be compatible with orbital theory, if the orbital is defined as space with 95% probability of finding electron. Similar is with resonance.

[Irlanur]

is how would that be compatible with orbital theory, if the orbital is defined as space with 95% probability of finding electron

I do not know that because that is simply not what an orbital is.

[kapital]

Than what is is?

[Enthalpy]

One difficulty is that resonance, aromaticity and some more are additions to older theories that imagine bonds between atom pairs - which are very useful theories - while QM and orbitals tell that electrons spread over more atoms. See: molecular orbitals.

Though, I haven't heard about a manageable version of molecular orbitals that would make quick, qualitative and reasonably reliable predictions about reaction mechanisms. Is there any? Or is someone willing to start this looong development?

Until then, bonds between atom pairs, plus resonances etc, which are known to be wrong, must be used because they bring results.