Hybridization, Hybridization Types, S And P Orbitals, Applications In Molecular Geometry

Salient features of Hybridization

1. The number of hybrid orbitals = Number of the atomic orbitals that get hybridized.
2. The hybridized orbitals are equivalent in energy and shape.
3. The hybrid orbitals are oriented in space along specific directions to minimize repulsion between electron pairs, resulting in a stable arrangement. Consequently, the type of hybridization serves as an indicator for the molecular geometry.
4. Hybrid orbitals generally form 𝛔 bond.

Conditions for hybridization

1. The orbitals present in the atom's valence shell undergo for hybridization.
2. The orbitals participating in hybridization must possess nearly identical energy levels.
3. Promotion of electron is not essential condition prior to hybridization.
4. It is not mandatory for only half-filled orbitals to participate in hybridization. In certain cases, even fully filled orbitals of the valence shell can participate in hybridization.

Types of Hybridization

1. sp hybridization
2. sp ² hybridization
3. sp ³ hybridization
4. sp ³ d hybridization

Types of Hybridization by Using s and p Orbitals:

1. sp Hybridization: In sp hybridization, one s and one p orbital combine to form two sp hybrid orbitals.

Types of Hybridization by Using s and p Orbitals
Participating Atomic Orbitals	Number of Hybridized Orbitals	Hybridization
1. One s + One p	2	sp

• Every sp hybridized orbital possesses an equal distribution of s and p characters, with 50% s character and 50% p character.
• Examples of sp hybridization includes:

2. sp ² Hybridization: sp ² hybridization involves the combination of one s and two p orbitals, resulting in three sp ² hybrid orbitals, characteristic of trigonal planar molecules like boron trifluoride (BF ₃ ).

• The three hybrid orbitals maintain coplanarity, forming an angle of 120° with each other. Each of the resulting hybrid orbitals contains 33.33% 's' character and 66.66% 'p' character.
• Examples of sp ² hybridization includes: BH ₃ , BF ₃

3. sp ³ Hybridization: sp ³ hybridization combines one s and three p orbitals to generate four sp ³ hybrid orbitals, responsible for the tetrahedral geometry observed in molecules like methane (CH ₄ )

• The angle between the sp ³ hybrid orbitals is approximately 109°28’
• Each sp ³ hybrid orbital is characterized by 25% s character and 75% p character.
• Examples of sp ³ hybridization includes CH ₄ , NH ₃ , H ₂ O, etc.

Types of Hybridization by Using s, p and d Orbitals:

4. sp ³ d Hybridization: The sp ³ d hybridization process entails the combination of one s orbital, three p orbitals, and one d orbital, resulting in the formation of five sp ³ d hybridized orbitals with uniform energy. These orbitals exhibit a trigonal bipyramidal geometry.

• Three hybrid orbitals are situated in a horizontal plane, inclined at an angle of 120° to each other, denoted as equatorial orbitals.
• The remaining two orbitals are found in the vertical plane, forming a 90° angle with the equatorial orbitals' plane, identified as axial orbitals.
• Example : PCl ₅

5. sp ³ d ² Hybridization: In sp ³ d ² hybridization, one s orbital, three p orbitals, and two d orbitals undergo intermixing to produce six identical sp ³ d ² hybrid orbitals.

• These six orbitals are oriented towards the corners of an octahedron, positioned at a 90° angle to each other.

6. sp ³ d ³ Hybridization: One s and three p and three d-orbitals of the outermost shell of an atom undergo mixing to give seven sp³d ³ hybrid orbitals. Out of these seven atomic orbitals, five are co-planar pointing towards the five corners of a regular pentagon and the remaining two are perpendicular to plane. The angle between any two sp³d³ orbitals in the pentagonal plane is 72° and two subtend an angle of 90° with the plane.

Example : IF ⁷

Percentage Character of Orbitals

Applications in Molecular Geometry :

Applications in Molecular Geometry
Hybrid Orbital	Hybridization	Atomic orbital involved	Shape	Bond Angle
2	sp	sp x / sp y / sp z	Linear	180°
3	sp 2	sp x p y / sp y p z / sp z p x	Trigonal planar	120 o
4	sp 3	sp x p y p z	Tetrahedral	109 o 28’
5	sp 3 d	sp x p y p z d 2 z	Trigonal bipyramidal	120 o , 90 o , 180 o
6	sp 3 d 2		Octahedral	90 o
7	sp 3 d 3		Pentagonal bipyramidal	72 o , 90 o , 180 o