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The p-orbitals oriented in the z-direction (p z) can overlap end-on forming a bonding (symmetrical) σ orbital and an antibonding σ* molecular orbital. In contrast to the sigma 1s MO's, the σ 2p has some non-bonding electron density at either side of the nuclei and the σ* 2p has some electron density between the nuclei.
Walsh diagrams in conjunction with molecular orbital theory can also be used as a tool to predict reactivity. By generating a Walsh Diagram and then determining the HOMO/LUMO of that molecule, it can be determined how the molecule is likely to react. In the following example, the Lewis acidity of AH 3 molecules such as BH 3 and CH 3 + is predicted.
According to molecular orbital theory, molecular orbitals are often modeled by the linear combination of atomic orbitals. In a simple diatomic molecule such as hydrogen fluoride (chemical formula: ), one atom may have many more electrons than the other. A sigma bonding orbital is created between the atomic orbitals with like symmetry.
Diagram of the HOMO and LUMO of a molecule. Each circle represents an electron in an orbital; when light of a high enough frequency is absorbed by an electron in the HOMO, it jumps to the LUMO. 3D model of the highest occupied molecular orbital in CO 2 3D model of the lowest unoccupied molecular orbital in CO 2
The qualitative approach of MO analysis uses a molecular orbital diagram to visualize bonding interactions in a molecule. In this type of diagram, the molecular orbitals are represented by horizontal lines; the higher a line the higher the energy of the orbital, and degenerate orbitals are placed on the same level with a space between them.
Added orbital diagrams for molecular orbitals. 16:49, 21 May 2015: 2,020 × 1,070 (138 KB) Officer781: 2pz MO in wrong orientation relative to the other orbitals per the LCAO notation. 16:40, 21 May 2015: 2,020 × 1,070 (138 KB) Officer781: Moved 2s orbital higher in energy as that MO has more hydrogen admixture.
[4] Lewis structures extend the concept of the electron dot diagram by adding lines between atoms to represent shared pairs in a chemical bond. Lewis structures show each atom and its position in the structure of the molecule using its chemical symbol.
Figure 5: Molecular orbital diagram depiction of frontier orbitals in methane and a basic ML 6 metal complex. As seen above, when a fragment is formed from CH 4, one of the sp 3 hybrid orbitals involved in bonding becomes a nonbonding singly occupied frontier orbital. The frontier orbital’s increased energy level is also shown in the figure.