Proper Overlap Between Atomic Orbitals

Orbital is described as a location with a high prospect of finding an electron. Atoms contain electrons that revolve all around the nucleus. When such orbitals overlap to create molecules via bonding, these orbitals are referred to as molecular orbitals. The overlapping atomic orbitals are the foundation of the molecular orbital concept. LCAO (linear combinations of atomic orbitals) are used to construct atomic orbitals. At the scientific level, this entails computing the overlap summation among two or more participating atomic orbital wave functions analytically. Before going on to the overlapping concept, let’s first discuss the atomic orbital definition to acquire a proper understanding.

Atomic Orbital

An atomic orbital is an area where an electron is most likely to be found. Quantum physics explains the likelihood of an atom’s electron’s placement. It does not describe the precise electron energy at one given moment. Heisenberg’s uncertainty rule explains it. The answers to the Schrodinger equation can be used to calculate an atom’s electron density. After knowing the atomic orbital definition, understand that the orbital will only contain two electrons. 

Sublevels of Atomic Orbitals

Sublevels of atomic orbitals are designated as s, d, p, and f. These orbitals come in a variety of forms. The “s” orbital is spherical and may accommodate up to two electrons. There is only one sub-energy level. The “p” orbital is structured like a dumbbell and can house up to six electrons. The shapes of the “d” and “f” orbitals are more complicated. The “d” level includes 5 sub-energy groups. It can store up to 10 electrons, whereas the “f” level contains seven sub-energy groups and can hold between ten to fifteen electrons. The energy of orbitals is presented in the form of s<p<d<f.

Atomic Orbital Overlapping

When two atoms unite to create a covalent bond, the energy of both atoms is lowest during the time they are so near that the orbitals are partly combined. This partial merger of atomic orbitals is referred to as atomic orbital overlapping. 

There are two overlapping orbitals: sigma (σ) orbitals and pi (π) orbitals. Both bonds are created by overlapping two orbitals, one on either atom. Whenever overlapping atomic orbitals happen between the nuclei of two or more atoms, a sigma bond is formed, also called the internuclear axis. As a result, atoms enter lower activation energy in which their valence electrons have opposing spins join up to generate a covalent bond.

Hydrogen Molecule (H2) Formation with Overlap of Atomic Orbital

Hydrogen Atom has its electronic configuration as 1s1. In its valence shell, it has one unpaired electron. As a result, the 1s orbital of the hydrogen atom is a bonding orbital. When two hydrogen atoms with opposing spin valence electrons approach one other, hydrogen atoms reduce, and so does the system’s potential energy. 

When the energies of attraction and repulsion among two hydrogen atoms are matched, the condition of the lowest potential energy is obtained. The system’s energy is at its lowest, and its stability is at its highest at this time. At this point, the orbitals of two hydrogen atoms meet, the spins of the electrons are neutralised, and a consistent covalent bond among hydrogen atoms is created, resulting in the formation of the H2 molecule. In this situation, the atomic orbital overlapping is greatest. It is known as the s-s overlap, and the connection created by the coaxial overlapping of two s orbitals is known as the s-s sigma bond.

Overlap Integral

Overlap Integral quantifies the overlapping atomic orbitals located on separate atoms. The number of orbitals of nearby atoms which are in the same areas of space is referred to as orbital overlap. Their overlap integral denotes the overlapping of an atom A’s and also an atom ‘s atomic orbital. It is described as SAB=∫ψ∗AψBdr expanding throughout all areas.

The overlap integral will be zero (0) if the wave functions need not overlap. If the wave functions contain favourable and unfavourable components that wipe off, the integral overlap can also be 0. When the overlap integral is 0, the wave functions are said to be orthogonal. As the distance between the variables approaches R = 0, the overlapping integral approaches the greatest overlap integral of S = 1. 

Conclusion

To summarise, an atomic orbital is the area of an atom that has the highest possibility of containing an electron. Furthermore, when two atoms unite to create a covalent bond, its potential is at its lowest when they are in very close proximity to one another such that their orbitals are substantially combined. Therefore, overlapping atomic orbitals refers to the partial merger of atomic orbitals. Other than this, we have also included an example of hydrogen molecule formation to better explain the overlapping in atoms