Question

As I was trying to understand resonance, I got to know that it was imaginary phenomenon and it is just a tool to explain mechanisms and structures that are unexplained by Lewis dot structures or structures where bonds are localized.

Hence its proper description is now done using molecular orbital theory which is beyond scope of studies for new students. Now after that I got to know that delocalization of electrons releases energy or increase stability of system, there are two explanations on Stack Exchange:

One of the explanation on Stack Exchange uses Particle in box concept to explain the phenomenon, that is: larger the length, less is the energy.

The other explanation involves saying delocalization causes charge cloud over large volume decreasing charge density, hence decreasing energy of system.

My question is: How can charge distribute over a volume if it is quantized? Does it come in discrete packets in form of electrons?

If this has any relation to probability of charge occurrence, the first explanation cannot be used, hence is there any rough, simple and intuitive explanation rather than using quantum mechanics and Particle in box etc.?

Answer 1

Electron delocalization can be explained by considering electron wave functions spreading out over multiple atoms, thus reducing energy due to lowered charge concentration. While electrons are indeed quantized, their probabilistic quantum behavior allows for the 'smearing' of their charge across a volume.

Step-by-step explanation:

To understand electron delocalization without diving deep into quantum mechanics or the particle in a box model, consider that electrons have wave-like properties according to the principles of quantum mechanics. In a molecule with delocalized electrons, the 'waves' of electron presence spread out across several atoms rather than being constrained between a pair of atoms.

It is true that electrons are quantized, meaning they exist as discrete particles. However, their quantum mechanical behavior allows for a probability distribution that describes where an electron is likely to be found at any time. This probability distribution can extend over several atoms, which describes how charge is 'smeared' over a larger volume in a delocalization scenario.