[Chemistry Class Notes] Orbital Overlap Pdf for Exam

In chemical bonds, an orbital overlap can be defined as the merging of orbitals on adjacent atoms in the same regions of space. Orbital overlap can lead to bond formation. During the orbital process, when two atoms come nearby then they penetrate each other’s orbital forming a new hybridized orbital in which the bonding pair of electrons reside. This hybridized orbital is stable since it has lower energy than the atomic orbital. It is in the minimum energy state. This partial penetration of the orbital to form a new hybridized orbital is known as orbital overlap. Two types of overlapping areas in the orbitals are sigma (σ) and pi (π). Both types of bonds are formed by overlapping two orbitals, one on each atom. Both types of overlapping orbitals can be related to the bond order. Single bonds contain one sigma bond. Double bonds contain one σ and one π bond, whereas triple bonds consist of one σ and two π bonds.

The extent of overlap is characterised by the participating atoms, their size and the valence electrons. Also, the greater the overlap, the stronger is the bond formed between the two atoms. Therefore, the orbital overlap theory explains how atoms combine by overlapping their orbital and thus forming a lower energy state in which their valence electrons pair up to form covalent bonds.

Directional Properties of Bond

The directional properties of the bond explain the molecular bond angles. The molecule of hydrogen is formed by an overlap of 1s orbital in a head-on collision.

Overlapping of Atomic Orbital

If any two atoms come in contact with each other then they form a bond, the bond can be positive, negative or even zero and that totally depends on the phase and sign of the two interacting orbitals.

1. Positive Overlapping of Atomic Orbital – When the phase of the two interacting atomic orbitals is the same, then the overlap is positive and this leads to bond formation. The phase of the two interacting orbitals (+ or -) depends on the sign of orbital wave function and is not related to the charge in any way.

2. Negative Overlapping of Atomic Orbital – When two interacting orbitals are in opposite phase, then the overlap generated is negative and the bond is not formed.

3. Zero Overlapping of Atomic Orbital – When two interacting orbitals are not overlapping each other in an orbital then it is known as zero overlapping of an atomic orbital.