Types of Molecular Orbitals

Molecular orbitals are determined by the linear combination of atomic orbitals with the distribution of electrons in each phase, lowering nuclei’s energy. Because of the distinct arrangement of electrons, their configuration, bond order, and bond energy are different. These segments are easily determined by the distinct types of molecular orbitals present in a specific element. According to the sign of molecular orbitals, they can attain distinct categories and types. They can be asymmetric or symmetric calculated at one instance concerning another called the nodal plane. 

Molecular Orbitals: An Overview

The molecular configurations are in computational demand to determine the electron configuration, electron density, bond strength, bond type, bond order etc. and some similar details of an atom. The molecular orbitals are a mathematical representation of the structure of an atom formed through the overlapping of atomic orbitals. The most important and simplified example of types of molecular orbitals is H2+ (dihydrogen ion). Here the molecular orbital is formed by exchanging a single electron with the placement of positively charged two nuclei. 

Types Of Molecular Orbitals:

Based on different types of molecules and their configuration, certain properties explain the types of molecular orbitals. All the types included in these categories vary according to the placement of electrons, bond formation, bond order and bond strength.

There are two basic types of molecular orbitals:

• Bonding molecular orbitals and 
• Antibonding molecular orbitals 

These molecular orbitals are formed by overlapping atomic orbitals or associate atoms. The molecular orbitals with the in-phase combination produce low-level energy termed sigma ‘s’ (σs). In this case, the electron density of the molecules lies in between the nuclei. 

In comparison, in the out-phase combination of molecules, the subtraction or addition of wave functions eventually produces the high energy molecular orbitals called sigma ‘s’ star (σs*). In the out-phase combination of molecular orbit, the presence of a node is experienced between the nuclei.

Electrons lying in the sigma ‘s’ molecular orbitals denote the lowering energy as the electrons placed here are attracted by nuclei of both the molecules. It makes the electrons stable, just like they attain the stability in an isolated state. In this state, adding electrons to the molecular orbitals will create an attractive force that will connect the nuclei with a strong bond. This type of molecular orbital is a bonding molecular orbital.  

Electrons present in the sigma ‘s’ star (σs*) molecular orbital are located in a distinct region at a specific distance from both nuclei. Hence, as a result, there is a repulsive force present between the nuclei and the electrons, which pull both apart. Such type of molecular orbitals is known as the antibonding molecular orbitals. 

Considering the electrons present in the ‘p’ orbital, the wave functioning among the molecular orbitals rises specific two lobes in distinct and opposite phases. In this case, when the orbital lobes of similar phases overlap, constructive wave interference increases electron density.

Similarly, when the orbital lobes of opposite phases overlap, the destructive wave interference lowers the electron density present in the molecular orbitals. In this phase, the nodes are created due to destructive wave interference. 

When the p orbitals overlap each other, they form sigma (σ) and sigma star (σ*) molecular orbitals. The sidewise overlapping of two ends forms the two types of molecular orbitals pi (π) bonding molecular orbitals and pi star (π *) molecular orbitals.

Important Types Of Molecular Orbital Formation: 

A certain important aspect explain the types of molecular orbitals with the specific bond formation and electron placement. Furthermore, it is explained by their associated properties and interaction methods between the electrons and nuclei. Below are the mentions:

• When the atomic orbitals overlap across the internuclear axis, it forms the σ (sigma) molecular orbital.
• In case when the two atomic orbitals overlap each other side-by-side, the molecular orbital formed this way is called π molecular orbital.
• All the ‘s’ molecular orbitals are arranged in spherical symmetry. The wave functions of all the molecules here attain the same size across all directions. 
• In the types of molecular orbitals of p-type, one side lobe consists of a positive (+) sign, and the other side lobes attain a negative (-) sign. 

Conclusion:

The molecular orbitals form distinct structures with different molecules and categorise themselves into different types of molecular orbitals. All the types of molecular orbitals depend upon the placement of electrons within the molecular orbitals. The bond formation of the molecular orbitals depends upon their charges and electrons exchange within the orbitals. The categorisation also depends on the attraction and repulsion forces between the electrons and nuclei present in the molecular orbit. The electron density in a certain type of molecular orbitals concerning wave interference denotes the constructive and destructive arrangement of the electrons.