But how do I know if the pi electrons in a molecule have delocalised charge? For example, how do I know if benzene has delocalised charge or not?Ygggdrasil said:Electrons in atoms and molecules are generally confined to specific volumes of space called orbitals. Most of these orbitals are between two different atoms (if the electrons are involved in a chemical bond) or around an individual atom (for electrons not involved in a chemical bond). In some types of chemical bonds, however, the orbital gets spread out between three or more atoms, sometimes encompassing an entire molecule. Because the electrons are not localized simply between two atoms but spread across a much larger area, we say that these electrons are "delocalized." If these electrons are giving the molecule an overall negative charge, delocalizing the electrons across the molecule delocalizes the negative charge across the entire molecule. Electrons must almost always be in pi bonds for them to become delocalized but not all electrons in pi bonds are delocalized.
The phenomenon of delocalization explains how molecules can act as if they have different arrangements of electrons (i.e. different resonance structures). As orbitals spread across a larger area, they become more stable (i.e. the energy of their ground state decreases), which is why resonance tends to be a stabilizing factor in molecular structures.
Delocalisation of charge refers to the distribution of electrons across multiple atoms or molecules, rather than being localized on a single atom. This can occur due to resonance, where electrons are able to shift between different possible arrangements within a molecule.
Resonance allows for delocalisation of charge by providing multiple possible arrangements for electrons to be distributed among atoms. This allows for the electrons to be spread out, rather than being confined to one specific location.
Delocalisation of charge can have a significant impact on the stability and reactivity of molecules. It can also affect the physical and chemical properties of a molecule, such as its color and bond lengths.
No, not all molecules can exhibit delocalisation of charge. It depends on the presence of conjugated systems, where multiple atoms are connected by alternating single and double bonds, as well as the ability for electrons to move freely within the molecule.
Delocalisation of charge is often explained through the use of resonance structures, which are different possible arrangements of electrons in a molecule. These structures depict the delocalisation of charge and help to explain the stability and reactivity of molecules.