The two models you mentioned, Molecular Orbital Theory (MOT) and Valence Bond Theory (VBT), offer different perspectives on chemical bonding and the role of electrons in molecules. Both models have their strengths and limitations, and neither model can be considered universally "true" or "false." Rather, they provide complementary explanations of chemical bonding based on different conceptual frameworks.
In Molecular Orbital Theory (MOT), the entire molecule is treated as a whole, and molecular orbitals are formed by the overlap and mixing of atomic orbitals from different atoms. MOT considers both valence electrons and core (inner) electrons to contribute to the molecular orbitals. The electron distribution in molecular orbitals is described by a set of molecular orbital diagrams, and the bonding and antibonding interactions are represented by the filling of these molecular orbitals.
On the other hand, Valence Bond Theory (VBT) focuses primarily on the concept of covalent bonding and describes chemical bonds as the overlap of atomic orbitals of the participating atoms. VBT emphasizes the role of valence electrons in forming these bonds. According to VBT, only the valence electrons are involved in the formation of covalent bonds, while the core electrons are considered to remain in the atomic orbitals and do not directly participate in bonding.
In reality, the electronic structure of molecules is complex, and it is a combination of both valence and core electrons that contributes to the overall bonding and properties of a molecule. The choice of which model to use depends on the specific context and the level of detail required for the analysis. MOT provides a more comprehensive description of molecular bonding, while VBT simplifies the picture by focusing on the valence electrons and covalent bonding.
It's important to note that these models are approximations and simplifications of the true nature of chemical bonding, which is a quantum mechanical phenomenon. Both models have their applications and limitations, and they are used as tools to help understand and predict the behavior of molecules.