What is Hybridisation in Chemistry?

Hybridisation is a fundamental concept in Chemistry that explains how atomic orbitals combine to form new, equivalent hybrid orbitals. These hybrid orbitals are crucial in determining the shape, bonding, and stability of molecules. By blending orbitals such as s, p, and d, hybridisation enables atoms to form stronger, directional bonds, leading to more stable molecular structures. 

This concept is essential for understanding molecular geometry, chemical reactions, and bonding behaviour in both natural and synthetic compounds. From sp hybridisation to sp³d², each type influences how atoms interact and form compounds. This page aims to provide a clear understanding of hybridisation, its types, examples, and its importance in the field of chemistry.

What is Hybridisation?

Hybridisation of atoms refers to the process of combining two atoms to form a new molecule. Hybridisation can occur spontaneously or as part of a chemical reaction.

Hybridisation involves taking two atoms from different elements and combining them to create a new substance. This process can happen spontaneously or be catalysed by another agent, such as heat or light. 

Key Features of Hybridisation

• Hybridisation is a process of mixing two or more atomic orbitals to form new hybrid orbitals.

• The number of hybrid orbitals formed is equal to the number of atomic orbitals involved in the process.

• The energy of these new hybrid orbitals is lower than that of the original atomic orbitals. This results in a decrease in overall energy for the atom, making it more stable.

• The shapes of molecules can be predicted by looking at the types of orbitals involved in their formation. For example, if two sp orbitals form a molecule, it will be linear in shape (like $C{{O}_{2}}$).

Rules for Finding the Type of Hybridisation

To understand the type of hybridisation in a compound or an ion, the following rules must be followed:

• Calculate the total number of valence electrons.

• Calculate the number of duplex or octet OR.

• Determine the number of lone pairs of electrons.

• Some used orbital = Number of duplex or octet + Number of lone pairs of electrons.

• If there is no lone pair of electrons then the geometry of orbitals and molecules is different.

Types of Hybridisation

The term 'hybridisation' refers to the process of combining two or more atomic orbitals into new orbitals with different shapes and energies. The resulting orbitals are called 'hybrids'. One type of hybridisation that can occur is called 'diagonal hybridisation'. This occurs when two orbitals on the same atom are combined to form a single hybrid orbital. The most common example of this is when two p-orbitals combine to form a single sp-hybrid orbital.

The resulting hybrids have properties that are intermediate between those of the original orbitals.

For example, an sp-hybridised orbital has one lobe that is larger than the other, and its energy is somewhere between that of an s-orbital and a p-orbital.

There are types of hybridisation: sp3, sp2 and sp. The type of hybridisation depends on the number of valence orbitals being combined. 

• Sp: This involves the combination of two orbitals - one s orbital and one p orbital. The resulting molecular orbital has 50% s character and 50% p character. Diagonal hybridisation of atom is present in acetylene (${{C}_{2}}{{H}_{2}}$).

SP Hybridisation

• Sp2 : This type involves the combination of three orbitals - one s orbital and two p orbitals. The resulting molecular orbital has 33% s character and 67% p character. Examples include ethene (${{C}_{2}}{{H}_{4}}$) and propene ($C{}_{3}{{H}_{6}}$). 

$s{{p}^{2}}$ Hybridisation

• Sp3 : This type of hybridization occurs when four orbitals are involved in bonding - one s orbital and three p orbitals. The resulting molecular orbital has 25% s character and 75% p character. Examples include methane ($C{{H}_{4}}$) and ethane (${{C}_{2}}{{H}_{6}}$).

$s{{p}^{3}}$ Hybridisation

• Sp3d : This type of hybridisation occurs when four orbitals are involved in bonding - one s orbital, three p orbitals and one d orbitals. One example of sp3d is pcl5.

$s{{p}^{3}}d$ Hybridisation

• Sp3d2 : This type of hybridisation occurs when four orbitals are involved in bonding - one s orbital, three p orbitals and two d orbitals. They are inclined at an angle of 90 degrees to one another.

sp3d2 Hybridisation

Shapes of Hybridisation

• Linear: The sp hybridisation is caused by the interaction of two-electron groups; the orbital angle is 180°.

• Trigonal planar: Three electron groups are involved, resulting in $s{{p}^{2}}$ hybridisation; the orbitals are 120° apart.

• Tetrahedral: Four electron groups are involved, resulting in $s{{p}^{3}}$ hybridisation; the orbital angle is 109.5°.

• Trigonal bipyramidal: Five electron groups are involved, resulting in $s{{p}^{3}}d$ hybridisation; the orbital angles are 90° and 120°.

• Octahedral: Six electron groups are involved, resulting in $s{{p}^{3}}{{d}^{2}}$ hybridisation; the orbitals are 90° apart.

The various molecular geometries predicted by the VSEPR theory are illustrated in the diagram below.

Shapes of Hybridisation

Solved Examples 

Q1. Explain the Hybridisation Of PCl5

Ans: The mixing of one s, three p, and one d orbital results in sp³d hybridisation, forming five hybrid orbitals. 

• Three equatorial bonds (120° apart).

• Two axial bonds (90° to the equatorial plane).

Explanation:

These orbitals arrange themselves in a trigonal bipyramidal geometry to minimise electron repulsion. The structure includes:

Lets Consider Metal Ion as X  with their Valance Electron and Ligand with no of atoms 

Phosphorus Valancy = 5

No. of Chlorine Atoms = 5

Phosphorus  (V.E)         Chlorine   (No Of Atoms)

X—---------------------------------Cl

X—---------------------------------Cl

X—---------------------------------Cl

X—---------------------------------Cl

X—---------------------------------Cl

So the Total No of Bonds Formed = 5 B.P + 0 L.P = 5 =TBP Geometry with , Sp3d Hybridisation .

Q.2 Explain the Hybridisation Of BF3 hybridisation

Ans: Lets Consider Metal Ion as X  with their Valance Electron and Ligand with no of atoms 

Boron Valancy = 3

No. of Fluorine Atoms = 3

Boron  (V.E)         Fluorine (No Of Atoms)

X—---------------------------------F

X—---------------------------------F

X—---------------------------------F

So the Total No of Bonds Formed = 3 B.P + 0 L.P = 5 =Triangular Planar Geometry and  SP2 hybridisation.

Q.3 Explain the NH3 hybridisation.

Ans: Lets Consider Metal Ion as X  with their Valance Electron and Ligand with no of atoms 

Nitrogen Valancy = 5

No. of Hydrogen Atoms = 3

Nitrogen  (V.E)         Hydrogen (No Of Atoms)

X—---------------------------------H

X—---------------------------------H

X—---------------------------------H

X—---------------------------------L.p

X—---------------------------------L.p

So the Total No of Bonds Formed = 3 B.P + 1 L.P =  4  Pyramidal Geometry and  SP3 

Hybridisation.

Note : 2 electrons contsitue 1 L.P

Q.3 Explain the SF4 hybridisation.

Ans: Let's Consider Metal Ion as X  with their Valance Electron and Ligand with no of atoms 

Sulphur Valancy = 6 

No. of Fluorine Atoms = 4

Sulphur  (V.E)         Fluorine (No Of Atoms)

X—---------------------------------F

X—---------------------------------F

X—---------------------------------F

X—---------------------------------F

X—---------------------------------L.p

X—---------------------------------L.p

So the Total No of Bonds Formed = 4 B.P + 1 L.P =  5  Seesaw Geometry and  SP3 

Hybridisation.

Note :2 electrons contsitue 1 L.P

Conclusion:

Hybridisation can seem complex, but Vedantu simplifies it with clear explanations, interactive lessons, and real-life examples. With expert tutors and engaging content, Vedantu makes mastering concepts like hybridisation easy and enjoyable for students, ensuring a strong foundation in chemistry.