Visualization of Orbitals (11) - Formation of Molecular Orbitals from the Interference of Atomic Orbitals

In 1811, A. Avogadro explained that elementary hydrogen exists as H-2 molecules. Avogadro's findings were almost completely ignored until S. Canizarro presented them at the Karlsruhe Conference in 1860. In 1916, G. N. Lewis described the sharing of electron pairs between atoms. This idea provides a picture of covalent bonding, however, quantum mechanics is needed to understand the nature of the chemical bond. In 1927, W. Heitler and F. London were succeeded in the first explanation of the chemical bond of molecular hydrogen based on the valence bond method. Molecular orbital (MO) method was also proposed to explain theoretically the nature of the chemical bond. Similar to photons, electrons show properties of particles and waves. A. Tonomura revealed that the wave character of electron is displayed when a beam of electron is passed through parallel slits thereby creating interference patterns [5, 7, 8]. Formation of two molecular orbitals phi(1) (bonding MO) and phi(2) (antibonding MO) from the interference of two hydrogen atomic orbitals chi(1) and chi(2) is shown in Figure 4. Electron density distribution in the 3-dimensional representation of the squares of hydrogen MOs are given in Figure 5. Difference electron density between vertical bar phi(1)vertical bar(2) and (vertical bar chi(1)vertical bar(2) + vertical bar chi(2)vertical bar(2)) in Figure 6 (c) and 7 (b) shows the intemuclear region having high probability densities of fmding an electron, to explain electron densities (-delta e) in this region could attract the hydrogen nuclei having plus electric charges.