Hybridization of Carbon

Carbon is one of the most important nonmetallic elements found in nature. It is a chemical element that is important to establish biological connections in the ecosystem. Atoms of some elements have the property of orbital hybridization, which is the mixing of atomic orbitals to form new hybrid orbitals. Carbon atoms possess this property and hence have the tendency to form different structures and have various properties by hybridization of orbitals. In fact, when it comes to carbon, several types of hybridization are possible. 

Usually, the s and p orbitals of the second shell in carbon combine together to turn into a hybridized form. Interestingly carbon can form different compounds by using different hybridizations.

Let us take a look at the various common hybridization types exhibited by carbon and their geometry.

What is Hybridization?

Hybridization is a process in which the orbitals of an element combine to form new orbitals for the atoms whereas the only difference between the new orbitals and the old orbitals is the energy and shape of the orbitals. It is used to learn what are the different types of bonds, bond lengths and energies that could be formed by an element. In a way, hybridization is an extension of the Valency theory as it helps in understanding the bonds. Through this hybridization, the energies in the elements redistribute to form equivalent energy levels. The new orbitals formed after hybridization are called hybrid orbitals. 

Important Features of Hybridization

• To undergo hybridization, atomic orbitals should have an equal number of energies in their orbitals.

• Any orbitals whether it is filled or half-filled can undergo hybridization.

• We can see an element undergoing hybridization only when it is forming a bond but not when it is isolated in a gaseous form.

• If we know the hybridization that a molecule undergoes, we can predict the shape it forms after the process.

• We can find out the number of hybrid orbitals by finding out the number of orbitals mixing to form bonds.

Types of Hybridization

Based on the orbitals involved in the hybridization process, it is divided into, sp3, sp2, sp, sp3d, sp3d2, sp3d3:

• Sp hybridization occurs when one orbital and one p orbital forms a bond to create a new hybridized orbital and the angle thus formed measures 180 degrees which are also known as linear bonds. This is also known as diagonal hybridization as it forms a 180 degrees angle between the ends.

• When one s orbital and 2 p orbitals in the same shell of an atom mix up to form three equal orbitals, it is called sp2 hybridization and it is also known as trigonal hybridization as it has a symmetric angle of 120 degrees between the three ends. The “p” character is dominant in this bond.

• One s orbital and 3 p orbitals hybridize together to form four equal orbitals with a different shape and energy in an sp³ hybridization and it is also known as the tetrahedral hybridization with an angle measuring 109.28 degrees between each end of the orbitals. Again the “p” character is dominant in this hybridization type accounting for around 77%.

• One “s” orbital, 3 “p” orbitals and one d orbitals hybridize to form an sp³d hybridized orbital with a different shape and energy, the horizontal plane measures 120 degrees and the vertical plane measures 90 degrees and it forms a trigonal bipyramidal symmetry.

• One “s” orbital, 3 “p” orbitals and 2 “d” orbitals hybridize to form an sp³d² bond and all the 6 orbitals are directed towards the centre with an inclination measuring 90 degrees.

Hybridization Types in Carbon

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At ground state, the electronic configuration of carbon is 1s 2 2s 2 2p 2 

Moreover, experimental evidence says that at the ground state it possesses 2 unpaired electrons in its 2p orbitals.

Now we will look at the hybridization states of Carbon.

Sp Hybridization of Carbon

When a carbon atom is bound to two other atoms with the help of two double bonds or one single and one triple bond, it can be in sp hybridization state. During the hybridization in the sp state, the molecules have a linear arrangement of the atoms with a bond angle of 180°.

Chemical bonds in alkynes that have triple bonds can be explained on the basis of sp hybridization. 2s orbital mixes with only one of the three p orbitals giving two sp orbitals and two remaining p orbitals. This results in sp hybridization. For example, sp hybridization of CO₂.

Sp2 Hybridization

In this type of hybridization, bonding takes place between 1 s-orbital with two p orbitals. Two single bonds and one double bond between three atoms form and the hybrid orbitals come together in a triangular arrangement. With 120° angles between bonds.

Example- Sp2 Hybridization of Graphite.

Sp3 Hybridization

In sp3 hybridization, the carbon atom is bonded to four other atoms. In this case, 1 s orbital and 3 p orbitals in the same shell of an atom combine to form four new equivalent orbitals. The arrangement of orbitals is tetrahedral with a bond angle of 109.5°.