Chemical bonding in the quantum and classical models

Many questions arise when writing reaction mechanisms, and therefore require answers for which the molecular formulas of the different species, reagents or intermediates, conform to the rules of classical and quantum models for the construction of different species, and show single, double or triple bonds, non-bonding doublets, electron vacancies and charges, as well as mesomeric forms where appropriate.The linear combination of atomic orbitals LCAO provides a visual representation of the energy levels associated with the different molecular orbitals formed from Atomic Orbitals (AO). LCAO is crucial for understanding the stability of molecules and the types of bonds they can form. Molecular Orbitals (MO) can be classified into two broad categories: bonding orbitals and antibonding orbitals. The quantum model is particularly well suited to describing diatomic molecules. It can help explain, for example, why some molecules exist in nature and others does not, such as rare gas and alkaline-earth molecules, the relative strength of chemical bonds, and the origin of certain physical properties such as the dipole moment and magnetism of molecules.The aim of this work is to compare the representation of chemical species between the quantum model (molecular orbital and hybridization theories) and the classical model (Gillespie theories and the systematic method of representing a molecule)