A Short Note on Hybridization

The process of merging two atomic orbitals to form a new type of hybridised orbitals is known as hybridization. As a result of this intermixing, hybrid orbitals with dramatically diverse energies, geometries, and so on are prevalent. Hybridization is mostly caused by atomic orbitals with the same energy level.Both totally filled and half-filled orbitals can participate in this process if their energies are equivalent. Hybridization is a valence bond theory extension that helps with bond formation, bond energy, and bond length.

Orbital Hybridisation

Orbital hybridisation (or hybridization) is a concept in valence bond theory that involves combining atomic orbitals to create new hybrid orbitals (with different energies, shapes, and other attributes than the component atomic orbitals) that are suitable for electron pairing to form chemical bonds. The valence-shell s orbital of a carbon atom, for example, interacts with three valence-shell p orbitals to generate four equivalent sp3 mixtures in a tetrahedral arrangement surrounding the carbon to connect to four other atoms. Hybrid orbitals are useful in describing molecular geometry and atomic bonding properties because they are symmetrically arranged in space. The most common way to make hybrid orbitals is to combine atomic orbitals with similar energies.

Hybridization Types

sp3

From the perspective of an atom, hybridisation describes the bonding of atoms. To connect to the four hydrogen atoms in a tetrahedrally coordinated carbon (e.g., methane CH4), the carbon must have four orbitals with the right symmetry.

The ground state configuration of carbon is 1s2 2s2 2p2, or to put it another way:

C ↑↓ ↑↓ ↑ ↑

1s 2s 2p 2p 2p

The carbon atom can create two covalent bonds with two hydrogen atoms using its two singly occupied p-type orbitals, creating the singlet methylene CH2, the simplest carbene. Excitation (or promotion) of one electron from the double occupied 2s orbital to the unoccupied 2p orbital produces four singly occupied orbitals, allowing the carbon atom to connect to four hydrogen atoms.

C* ↑↓ ↑ ↑ ↑ ↑

1s 2s 2p 2p 2p

sp2

In a similar way, various carbon compounds and molecules can be explained. The carbons in ethene (C2H4), for example, have a double bond between them.

Carbon sp2 hybridized in this molecule because the double bond between the carbons requires only one (pi) bond, and only three bonds are generated per carbon atom. The 2s orbital is mixed with only two of the three accessible 2p orbitals, generally labelled 2px and 2py, in sp2 hybridisation. Unhybridized is the third 2p orbital (2pz).

C* ↑↓ ↑ ↑ ↑ ↑

1s sp2 sp2 sp2 2p

resulting in three sp2 orbitals and one p orbital remaining The two carbon atoms in ethylene (ethene) create a bond by overlapping one sp2 orbital from each carbon atom. 2p–2p overlap forms the connection between carbon atoms perpendicular to the molecular plane. By s–sp2 overlap, each carbon atom generates covalent C–H bonds with two hydrogens, all with 120° bond angles. Experimental data shows that all hydrogen–carbon bonds are of similar strength and length.

sp

Triple hybridization explains the chemical bonding of compounds containing triple bonds, such as alkynes. Only one of the three p orbitals is combined with the 2s orbital in this model.

C* ↑↓ ↑ ↑ ↑ ↑

1s sp sp 2p 2p

resulting in two sp orbitals and two p orbitals remaining In acetylene (ethyne) (C2H2), the chemical bonding consists of a sp–sp overlap between the two carbon atoms generating a bond and two extra bonds created by p–p overlap. Each carbon also forms a s–sp overlap with hydrogen at 180° angles.

sp3d Hybridization

The mixing of orbitals of one’s’, three ‘p’, and one ‘d’ to create five sp3d hybridised orbitals of equivalent energy is known as sp3d hybridization. They have a trigonometric bipyramidal geometry.

Triangular/ trigonal bipyramidal geometry is formed by combining the orbitals of s, p, and d.

“Equatorial orbitals” are formed when three hybrid orbitals develop on a horizontal plane, establishing a 120° angle with each other.

The remaining two orbitals create a 90-degree angle and lie in the axial orbitals, a vertical plane of equatorial orbitals.

Phosphorus pentachloride is an example (PCl5)

sp3d2 Hybridization

This hybridization has a combination of 1s, 3p, and 2d orbitals, which combine to generate six identical “sp3d2 hybrid orbitals.”

These newly produced six orbitals are oriented toward the octahedron’s angles.

At a 90-degree angle to one another, the hybridization takes place.

Trigonal Bipyramidal Molecular Geometry

In chemistry, a trigonal bipyramid formation is a molecular shape with one atom in the centre and five other atoms in the corners of a triangular bipyramid.Because there is no geometrical configuration with five terminal atoms in equivalent places, the bond angles surrounding the central atom are not identical (see also pentagonal bipyramid). In the gas phase, phosphorus pentafluoride (PF5) and phosphorus pentachloride (PCl5) are examples of this molecular geometry. 

Formula for Hybridization

Hybridization=1/2[V+M-C+A]

Here,

The number of valence electrons is denoted by v, and

m stands for monovalent.

c = charge that is positive

a = charge that is negative

Conclusion

Hybridization is a concept that can be used to describe both organic and inorganic chemistry. Its importance in organic chemistry arises from the fact that it is the only simple model that can explain organic molecules’ molecular geometry (roughly).