Hybridisation

The intermixing of atomic orbitals typically results in the formation of hybrid orbitals with completely different energies, shapes, and other characteristics. 

The atomic orbitals with the same energy level are the ones that are most involved in hybridisation. 

In this process, however, both fully filled and half-filled orbitals can participate, as long as they have the same amount of energy as one another.

As an alternative, we can describe hybridisation as an extension of valence bond theory that aids in the understanding of bond formation, bond energies, and bond lengths in a variety of systems. 

What is the definition of hybridisation?

When two atomic orbitals combine to form a hybrid orbital in a molecule, the energy of the orbitals of individual atoms is redistributed to give orbitals of equivalent energy. 

This occurs when two atomic orbitals combine to form a hybrid orbital in a molecule. 

Hybridisation is the term used to describe this process. The process of hybridisation involves the mixing of atomic orbitals with similar energies. It is most commonly associated with the merging of two ‘s’ orbitals or two ‘p’ orbitals, or the mixing of an ‘s’ orbital with a ‘p’ orbital, as well as the mixing of an ‘s’ orbital with a ‘d’ orbital, among other things.

Hybrid orbitals are the new orbitals that are formed as a result of this process. More importantly, hybrid orbitals are extremely useful in explaining atomic bonding properties as well as molecular geometry, among other things.

Consider the case of a carbon atom for the sake of illustration. This atom forms four single bonds in which the valence-shell s orbital mixes with three valence-shell p orbitals, resulting in a total of four single bonds. 

This combination results in the formation of four sp3 mixtures that are equivalent. A tetrahedral arrangement will form around the carbon atoms, which will be bonded to four different atoms in this case.

Hybridisation’s most important characteristics

1. Hybridisation occurs when atomic orbitals with equal energies come together.

2. A hybrid orbital is formed when two atomic orbitals mix together in the same way as an atomic orbital.

3. It is not necessary for all of the half-filled orbitals to participate in the hybridisation process to occur. There is also the possibility of completely filled orbitals with slightly different energies taking part in the game.

4. Hybridisation occurs only during the bond formation process, and not in a single gaseous atom on its own.

5. If the hybridisation of the molecule is known, it is possible to predict the shape of the molecule in advance.

6. The larger lobe of the hybrid orbital always has a positive sign, whereas the smaller lobe on the opposite side always has a negative sign. 

Hybridisation can take many forms-

The hybridisation can be classified as sp, sp2 , sp3, sp3d, sp3d2, or sp3d3 depending on the types of orbitals that are involved in the mixing.They are-

sp hybridisation

sp hybridisation is observed when one s and one p orbital in the same main shell of an atom mix to form two new equivalent orbitals. The hybridised orbitals that are formed as a result of this process are referred to as sp hybridised orbitals. It results in the formation of linear molecules with an angle of 180°.

One of the most common types of hybridisation is the mixing of one ‘s’ orbital and one ‘p’ orbital of equal energy to produce a new hybrid orbital known as a sp hybridised orbital. This type of hybridisation is most common in the chemical industry.

In some circles, sp hybridisation is referred to as diagonal hybridisation.

sp hybridised orbitals have an equal amount of s and p character – 50 percent s and 50 percent p character – and are therefore divisible by two.

Examples of sp hybridisation include the following:

All beryllium compounds, such as BeF2, BeH2, and BeCl2, are toxic. 

All carbon-containing triple bonds, such as C2H2, are present in all compounds. 

sp2 hybridisation-

When one s and two p orbitals of the same shell of an atom combine to form three equivalent orbitals, this is referred to as sp2 hybridisation. The new orbitals that have formed are referred to as sp2 hybrid orbitals.

sp2 hybridisation is also referred to as trigonal hybridisation in some circles.

It entails the mixing of one ‘s’ orbital with two ‘p’ orbitals of equal energy to produce a new hybrid orbital known as sp2, which is a new hybrid orbital.

A mixture of s and p orbitals that are formed in trigonal symmetry and are kept at 1200℃ 

Despite their differences, all three hybrid orbitals remain in the same plane and form a 120° angle with one another. Each of the hybrid orbitals that have been formed has a character that is 33.33 % ‘s’ and 66.66 % ‘p’ in it.

The triangular planar shape of the molecules in which the central atom is linked to three other atoms and is sp2 hybridised is a result of the sp2 hybridisation of the central atom.

Illustrations of sp2 hybridisation

All of the boron compounds, such as BF3, BH3, and BH4

Ethylene is a carbon compound that contains a carbon-carbon double bond, as are all carbon compounds (C2H4)

sp3 hybridisation

Tetrahedral hybridisation, also known as sp3, occurs when one s orbital and three p orbitals from the same shell of an atom combine to form four new equivalent orbitals. 

This type of hybridisation is characterised by the formation of four new equivalent orbitals. The new orbitals that have formed are referred to as sp3 hybrid orbitals.

These are oriented in the direction of the four corners of a regular tetrahedron and form an angle of 109°28′ with respect to one another.

In the sp3 hybrid orbital, the angle between the two orbitals is 109.280 degrees.

Each sp3 hybrid orbital has 25 % s character and 75 % p character, making it a hybrid sp3 orbital.

Ethane (C2H6) and methane are two examples of sp3 hybridisation.

sp3d hybridisation

In sp3d hybridisation, the 1s orbital, 3p orbitals, and 1d orbital are mixed together, resulting in the formation of 5 sp3d hybridised orbitals with equal energy. They have a bipyramidal geometry that is trigonal.

The trigonal bipyramidal symmetry is formed by the combination of the s, p, and d orbitals.

The equatorial orbitals are three hybrid orbitals that lie in the horizontal plane and are inclined at an angle of 120° to one another. They are located in the horizontal plane and are inclined at an angle of 120° to one another.

Anterior and axial orbitals are the two remaining orbitals that are located in the vertical plane at a 90° angle to the equatorial orbitals and are known as axial orbitals.

For instance, hybridisation in Phosphorus pentachloride is an example (PCl5)

sp3d2 hybridisation 

The 1s, 3p, and 2d orbitals of sp3d2 hybridisation are intermixed to form six identical sp3d2 hybrid orbitals after the hybridisation process.

These six orbitals are oriented in the direction of the octahedron’s four corners.

Each of them is inclined at a 90° angle with respect to the other.

Conclusion-

When two atomic orbitals combine to form a hybrid orbital in a molecule, the energy of the orbitals of individual atoms is redistributed to give orbitals of equivalent energy.