![]() Combination of two hydrogen 1 s atomic orbitals leads to two H 2 molecular orbitals. Similarly, the subtractive combination is a single molecular orbital with the shape of an elongated dumbbell.įigure 1.18 Molecular orbitals of H 2. ![]() Note that the additive combination is a single, egg-shaped, molecular orbital it is not the same as the two overlapping 1 s atomic orbitals of the valence bond description. The additive combination leads to formation of a molecular orbital that is lower in energy and roughly egg-shaped, while the subtractive combination leads to a molecular orbital that is higher in energy and has a node between nuclei ( Figure 1.18). There are two ways for the orbital combination to occur-an additive way and a subtractive way. In the H 2 molecule, for example, two singly occupied 1 s atomic orbitals combine to form two molecular orbitals. Like an atomic orbital, a molecular orbital has a specific size, shape, and energy. Just as an atomic orbital, whether unhybridized or hybridized, describes a region of space around an atom where an electron is likely to be found, so a molecular orbital describes a region of space in a molecule where electrons are most likely to be found. Molecular orbital (MO) theory describes covalent bond formation as arising from a mathematical combination of atomic orbitals (wave functions) on different atoms to form molecular orbitals, so called because they belong to the entire molecule rather than to an individual atom. We’ll return to this topic in Chapters 14, 15, and 30 for a more in-depth discussion. Having now seen the valence bond approach, which uses hybrid atomic orbitals to account for geometry and assumes the overlap of atomic orbitals to account for electron sharing, let’s look briefly at the molecular orbital approach to bonding. We said in Section 1.5 that chemists use two models for describing covalent bonds: valence bond theory and molecular orbital theory. Describing Chemical Bonds: Molecular Orbital Theory.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |