Lecture No. 03
Hybridisation
Contents
• Hybridisation
• SP2
• Sp3
• Sp
• Bong angles
• Geometry
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Learning Objectives
At the end of this lecture, student will be able to
• Explain different types of hybridisation
• Relate hybridisation to geometry of molecules
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Hybridization
• 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
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Hybridisation
• Mixing of orbitals
• To attain equal energy and stability
• Sp3
• Sp2
• Sp
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Sp3 hybridization
• Axes of the four sp3 hybrid orbitals are directed toward the corners
of a regular tetrahedron
• sp3 hybridization results in bond angles of approximately 109.5°
• Each sp3 orbital has 25% s-character and 75% p-character
• Because those are the percentages of the orbitals combined when
constructing them
• one 2s orbital, three 2p orbitals
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Sp3 Hybridisation Contd…
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Sp3 Hybridisation Contd…
The four orbitals are directed toward the
corners of a tetrahedron, causing each
bond angle to be 109.5°
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Sp2 hybridization
• Bond angles of approximately 1200
• combination of one 2s atomic orbital wave function and two 2p
atomic orbital
• forms three equivalent sp2 hybrid orbital
• Axes of the three sp2 hybrid orbitals lie in a plane and are directed
toward the corners of an equilateral triangle
• three equivalent sp2 orbitals along with the remaining unhybridized
2p atomic orbital
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Sp2 hybridization
• Each sp2 orbital has 33% s-character and 67% p-character
• one 2s orbital, two 2p orbitals
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Borane (BH3)
• Sp2 hybridization
• Exception to octet rule
• According VSEPR theory, trigonal planar with bond angle 1200
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Sp2 Hybridisation
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Sp2 Hybridisation Contd…
Trigonal planar carbon, 120o
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sp hybridization
• Bond angle of approximately 1800
• combination of one 2s atomic orbital and one 2p atomic orbital
• produces two equivalent sp hybrid orbital
• axes of the unhybridized 2p 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
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Sp Hybridisation
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Sp Hybridisation
Linear molecule
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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
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Summary Contd…
• 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°
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Problem-1
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Problem-2
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Problem-3
• Has two linear sp carbon atoms (C2 and C3)
• Two trigonal sp2 carbon atoms (C5 and C6)
• Two tetrahedral sp3 carbon atoms (C1 and C4)
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Thank You
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