Characteristics of Bonding Molecular Orbitals

In MOT (molecular orbital theory), new molecular orbitals form through a mathematical method termed as linear combination of atomic orbitals. This theory takes the concept of atomic orbitals overlapping to another stage. According to the molecular orbital hypothesis, the atomic orbitals unite and generate molecular orbitals. The molecular orbitals can be segregated into non-bonding, bonding and antibonding molecular orbitals. Here, the below article will discuss the bonding molecular orbitals (BMO) and their characteristics. 

What are Molecular orbitals?

In chemistry, a molecular orbital is a mathematical function that specifies the location of an electron in a molecule. A molecular orbital can calculate physical and chemical factors like the probability of finding an electron in a specific location. It also depicts the wave-like behaviour of electrons.

The region of space where a molecule’s valence electron is most usually present is known as a molecular orbital. A molecular orbital is filled when it has two electrons with opposing spins, similar to atomic orbitals.

Molecular orbitals can be classified into three types, namely non-bonding, bonding and antibonding molecular orbitals. First, let’s discuss the bonding molecular orbitals (BMOs) in detail. 

Bonding molecular orbitals: what are they?

Bonding interactions are constructive interactions among atomic orbitals. The BMO is created when 2 atomic orbitals from 2 separate atoms overlap. This overlapping causes both the atomic orbitals to mix and produce these molecular orbitals. The atomic orbitals must have equivalent energies and perfect symmetry to be combined.

BMOs (bonding molecular orbitals) have a higher density of electrons than ABMOs. The bonding MOs are of lower energy than the parent atomic orbitals that unite to form them. They contribute to forming chemical bonds. Since lower energy levels signal more stability, these bonding MOs have high stability. The BMOs help determine molecular geometry.  

For instance, the two independent H atoms have similar atomic orbitals in the H2 molecular orbital. While generating the dihydrogen molecule, the individual valence orbitals may combine in phase to form bonding molecular orbitals or BMOs. In this case, the electron density would be between the atomic nuclei. The valence orbitals may also join out of phase to form antibonding orbitals. However, in this case, the density of electrons will be all around the atom except in the space between the atomic nuclei. 

When the 2 hydrogens are diatomic, bonding orbitals result in a more stable species. Antibonding orbitals are much less stable. Since there is little or no density of electrons at the central space, the two nuclei of the same charge repel each other. 

Bonding molecular orbitals: characteristics

The bonding molecular orbital has certain properties, which are as follows:

• The bonding molecular orbital has lesser energy and better stability than the combining atomic orbitals. 
• They are produced due to the atomic orbitals’ additive influence.
• The likelihood of locating the electron in the internuclear area of the bonding molecular orbital or BMO is higher than that of merging atomic orbitals.
• The two atoms are attracted to one another because of the bonding molecular orbital electrons.

Dissimilarities Between Bonding and Antibonding Molecular Orbitals

Here is the difference between bonding and antibonding molecular orbitals in a tabular form. 

Conclusion

Because of their broad applicability, molecular orbitals, notably the bonding orbital, are taught in various chemistry courses, from analytical to organic and even physical chemistry. Several chemists employ this concept through band theory which is an extension of the MOT or molecular orbital theory, in various spectroscopic methods, computations, and material chemistry.