**Hybridisation**

__Contents__

• Hybridisation

• SP2

• Sp3

• Bong angles

• Geometry

__Learning
Objectives__

**At the end of this
lecture, student will be able to**

• Explain different types of hybridisation

• Relate hybridisation to geometry of molecules

__Hybridisation__

__Hybridisation__

• Hybrid orbital- An orbital formed by the combination of

two or more atomic orbitals

• Hybridization- The combination of atomic orbitals of

different types

• Number of hybrid orbitals formed is equal to the number of

atomic orbitals combined

• sp3 Hybrid Orbitals—Bond Angles of Approximately 109.5°

• Combination of the 2s atomic orbital and three 2p atomic

orbitals forms four equivalent sp3 hybrid orbitals

• Mixing of orbitals

• To attain equal energy and stability

• Sp3

• Sp2

• Sp

__Sp3__

Hybridisation

__Sp3__

Hybridisation

Hybridisation

• Axes of

the four *sp*3 hybrid orbitals are directed toward the corners of a

regular tetrahedron

• *sp*3 hybridization results in bond angles

of approximately 109.5°

• Each *sp*3

orbital has 25% *s*-character and 75% *p*-character

• Because

those are the percentages of the orbitals combined when constructing them

• one 2*s
*orbital, three 2

*p*orbitals

The four orbitals are directed toward the corners of a

tetrahedron, causing each bond angle to be 109.5°

__Sp__^{2}

Hybridisation

__Sp__

Hybridisation

^{2}Hybridisation

• Bond

angles of approximately 120^{0}

• Combination

of one 2*s *atomic orbital wave function and two 2*p *atomic orbital

• Forms

three equivalent *sp*2 hybrid orbital

• Axes of

the three *sp*2 hybrid orbitals lie in a plane and are directed toward the

corners of an equilateral triangle

• Three

equivalent *sp*2 orbitals along with the remaining unhybridized 2*p *atomic

orbital

• Each sp2 orbital has 33% s-character and 67% p-character

• One 2s orbital, two 2p orbitals

**Borane**

(BH_{3})

(BH

_{3})

• Sp2

hybridization

• Exception

to octet rule

• According

VSEPR theory, trigonal planar with bond angle 120^{0}

Trigonal planar carbon, 120^{o}

__sp hybridization__

__sp hybridization__

• Bond

angle of approximately 180^{0}

• Combination

of one 2*s *atomic orbital and one 2*p *atomic orbital

• Produces

two equivalent *sp *hybrid orbital

• Axes of the

unhybridized 2*p *atomic orbitals are perpendicular to each other and to

the axis of the two *sp *hybrid orbitals

• Each *sp
*orbital has 50%

*s*-character and 50%

*p*-character

__Summary __

• Sp3, sp2 and sp

hybridisation

• Example for Sp3 hybridisation is methane and ethane

• Four Sp3 hybridized orbitals

• All bonds are sigma bonds

• Geometry of methane is tetrahedral and bond angle is

109.5°

• Example for sp2 hybridisation is ethene

• Three Sp2 hybridized orbitals

• One unhybridised p- orbital oriented perpendicular to the

plane

• One π bond is formed

• Geometry of ethene is trigonal and bong angle is 120°

• Example

for sp hybridisation is ethyne

• Two Sp^{
} hybridized orbitals

• Two

unhybridised P- orbitals oriented pependicular to the plane

• Two π-bonds are formed

• Geometry

of ethyne is linear and bond angle is 180°