Hybridization-1

Bonding in Molecules
Part-III: Hybridization-I
(Remedial Teaching Lecture-1)
Prepared by
D. R. Shinde
Associate Professor in Chemistry
Department of Chemistry
P.D.E.A’s.
Prof. Ramkrishna More
Arts, Commerce and Science College Akurdi,
Pune-411044

Concept of Hybridization
3. In excited state pure orbital of an atom mix with each other to
form hybrid orbitals.
 Need of Hybridization: Concept of hybrid orbitals is introduced to explain actual
geometries of molecules and bond angles in molecules.
 Steps in formation of hybrid orbitals:
 Condition of hybridization:
1. During chemical reaction atom undergoes excitation.
2. Electronic excitation may take place from full filled to empty
orbitals.
1. Pure orbital of same atom take part in formation of hybrid orbitals.
2. They should have nearly same energy.
3. No of hybrid orbitals formed are equal to number of pure orbitals involved in hybridization
process.
05/08/2020
D. R. Shinde, Asociate Prof., P.D.E.A's. Prof Ramkrishna More
College, Akurdi, Pune
2

1. Hybrid orbitals have different shape and orientation in space than pure orbitals.
 Characteristics of Hybrid Orbitals:
2. All hybrid orbitals have same shapes.
3. Electrons from pure orbitals are filled into hybrid orbitals.
4. Hybrid orbitals are occupied in a space around nucleus so that they have maximum
distance from each other.
 Naming of Hybrid orbitals: They are named after
pure orbitals used for the hybridization.
i. s + p orbital form two sp hybrid orbitals
ii. s + 2p orbital form three sp2 hybrid orbitals
iii. s + 3p orbital form four sp3 hybrid orbitals
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 1. sp hybridization: One s and one p orbitals of same atom having nearly same
energies mix with each other to form two sp hybrid orbitals.
Types of Hybridization-Involving s and p Orbitals
i. Why two hybrid orbitals are formed? Two pure orbitals are involved in
hybridization hence Two sp hybrid orbitals are formed.
ii. Why angel between hybrid orbitals is 180˚? They lie at 180˚ to each other since this
angle gives maximum distance between hybrid orbitals from each other.
+
s orbital pz orbital
orbitals
z
y
x
- -
-
Two sp hybrid orbitals
-+
Two sp hybrid orbitals
in an atom are themselves
orientated at 180˚ to each
other
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Example CO2 Molecule:
 C is central atom. Hence consider hybridization of C atom
 C Electronic Configuration is - 1s2, 2s2, 2pz
1 2py
1 2px
0
 C outermost shell orbitals are - 2s2, 2pz
1 2py
1 2px
0
 Orbitals undergo hybridization during the formation of CO2 molecule i.e. when C and O2 gas interacts
with each other to form CO2 molecule.
 During formation of CO2 molecule the steps are -
i. Excitation of C atom - where one electron 2s
orbitals pass to empty 2pz orbital.
iii. Hybridization: In CO2, C undergoes sp
hybridization i.e. 2s and 2pz orbital to form two
2sp hybrid orbitals.
ii. C in excited state
Electronic configuration:
↑ ↑ ↑ ↑
2s1 2pz
1 2py
1 2px
1
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C in excited state – Hybridization : ↑ ↑ ↑ ↑
Two sp1 hybrid
orbitals
2px and 2pz
orbitals
 Two sp hybrid orbitals are half filled. They lie along internuclear axis.
s orbital pz orbital
orbitals
z
y
x
- -+ Two sp hybrid orbitals
in an atom orientated at
180˚ to each other
-+
-
px
py
sp hybrid
Hybrid and pure
orbitals of C atom
z
y
x
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pz orbital
O atom
-
pz orbital
O atom
-+-+
-
px
py
sp hybrid
z
y
x
+
O in excited state – electronic configuration: ↑↓ ↑↓ ↑ ↑
2s2 2px
2 2py
1 2pz
1
O atom has half filled 2pz and 2py orbitals which are taking part in bonding.
2pz orbitals of two oxygen
atom will overlap with two
half filled 2sp hybrid
orbitals of C to from sigma
bond.
O – C – O sigma bond formation
pz orbital
O atom
-
pz orbital
O atom
--+
-
px
py
sp
hybrid
z
y
x
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 pi bond formation:
 i) 2py orbitals of one oxygen atom will overlap with two half filled 2py orbital of C on one
side.
 ii) On another side 2px orbitals of one oxygen atom will overlap with two half filled 2px
orbital of C to form pi bond.
-
px
pyO atom
2py orbital O atom
2px orbital
O – C – O Pi bond formation By lateral overlap of C
and O orbitals
-
π π
Internuclear
axis
C atom
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CO2 Molecule: O = C = O
i) Structure – linear, ii) O-C-O Bond angle - 180˚
Reason: sp hybridization of C atom. sp hybrid orbital
lie at 180˚. They take part in σ bond formation. Σ bond
decide geometry of molecule.
-+
-
px
py
-
O atom
2py orbital
O atom
2px orbital
O = C = O σ and Pi bond formation
by C and O orbital overlap
-
σσ
π π
Orbital overlap between C and O atoms to form σ and Pi bonds
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 2. sp2 hybridization: One s and two p orbitals of same atom having nearly same
energy mix with each other to form three sp2 hybrid orbitals.
-+ -
-
Three sp2 hybrid
orbitals
Three sp2 hybrid
orbitals in an atom
arranged at 120˚ to
each other
S orbital pz and py
orbital orbitals
-
i. Why three hybrid orbitals are formed? Three
pure orbitals are involved in hybridization hence
Three sp2 hybrid orbitals are formed.
ii. Why angel between hybrid orbitals is 120˚?
They lie at 120˚ to each other since this angle
gives maximum distance among hybrid orbitals
from each other.05/08/2020
10

Example sp2 Hybridization: BF3 Molecule:
 B is central atom. Hence consider hybridization of B atom
 B Electronic Configuration is - 1s2, 2s2, 2pz
1 2px
0 2py
0
 B outermost shell orbitals are - 2s2, 2pz
1 2px
0 2py
0
 Orbitals undergo hybridization during the formation of BF3 molecule i.e. when B and F2 gas interacts
with each other to form BF3 molecule.
 During formation of BF3 molecule the steps are -
i. Excitation of B atom - where one electron 2s
orbitals promoted to empty 2py orbital.
iii. Hybridization: In BF3, B undergoes sp2 hybridization
i.e. 2s, 2pz and 2px orbital undergoes sp2 to form
three sp2 hybrid orbitals.
ii. B in excited state
↑ ↑ ↑
2s1 2pz
1 2px
1 2py
0
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 Three sp2 hybrid orbitals are half filled. They take part in the formation of three B-F sigma
bonds.
F in ground and excited state
– electronic configuration:
↑↓ ↑↓ ↑↓ ↑
2s2 2px
2 2py
2 2pz
1
F atom has half filled 2pz orbital which take
part in bonding. It form axial overlap with
half filled hybrid orbital of B atom to form
B-F sigma bond
+
S orbital pz and py
orbital orbitals
-
-
z
y
x
Three sp2 hybrid
orbitals
Three sp2 hybrid orbitals in an atom
arranged at 120˚ to each other. All
they are half filled.
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 BF3 Molecule: i) Structure – Trigonal planar,
ii) F - B – F Bond angle - 120˚
Reason: sp2 hybridization of B atom. Three sp2
hybrid orbital lie at 120˚. They take part in σ
bond formation and give bond angle 120 ˚
and therefore geometry is trigonal planar.
BF
F
F
120˚
 Three half filled 2pz orbitals of F atoms give axial overlap with half filled hybrid orbital of
B atom to form B-F sigma bond.
Three sp2 hybrid
orbitals of B
pz orbital
F atoms
-3 +
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 3. sp3 hybridization: One s and three p orbitals of same atom having nearly
same energy mix with each other to form four sp3 hybrid orbitals.
i. Why Four hybrid orbitals are formed? Four
pure orbitals are involved in hybridization hence
four sp3 hybrid orbitals are formed.
ii. Why angel between hybrid orbitals is 109˚28˝?
They lie at 109˚28˝ to each other since this angle
gives maximum distance among hybrid orbitals
from each other.
S orbital pz, px and py
orbital orbitals
-
-
z
y
x
Four sp3 hybrid
orbitals
Four sp3 hybrid orbitals in
an atom arranged at
109˚28˝ to each other
-
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Example sp3 Hybridization: CH4 Molecule:
 C is central atom. Hence consider hybridization of C atom
 C Electronic Configuration is - 1s2, 2s2, 2pz
1 2px
1 2py
0
 Orbitals undergo hybridization during the formation of CH4 molecule i.e. when C and H2 gas interacts
with each other to form CH4 molecule.
 During formation of CH4 molecule the steps are -
i. Excitation of C atom - where one electron 2s
orbitals promoted to empty 2pz orbital.
iii. Hybridization: In CH4 C undergoes sp3
hybridization i.e. 2s, 2pz, 2px and 2py orbital
undergoes sp3 to form four sp3 hybrid orbitals.
ii. C in excited state
↑ ↑ ↑ ↑
2s1 2pz
1 2px
1 2py
1
 C outermost shell orbitals are - ↑↓ ↑ ↑
2s2 2pz
1 2px
1 2py
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 Four sp3 hybrid orbitals are half filled. They take part in the formation of three C – H sigma
bonds.
H in ground and excited state
– electronic configuration:
↑
1s1
H atom has half filled 1s orbital which take
part in bonding. It form axial overlap with half
filled hybrid orbital of C atom to form C-H
sigma bond
s orbital pz, px and py
of C atom orbitals of C atom
-
-
z
y
x
Four sp3 hybrid
orbitals
Four sp3 hybrid orbitals in
an atom arranged at
109˚28˝ to each other
-
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 sp3 hybrid orbitals are oriented at the
corner of tetrahedron with 109˚28˝ angle
with each other. Hence they give
tetrahedral geometry to the molecule and
bond angle 109˚28˝.
 Four half filled 1s orbitals of H atoms give axial overlap with half filled hybrid orbital of
C atom to form C-H sigma bonds.
109˚28˝
Tetrahedral structure of
CH4 molecule
S orbital
H atom
z
y
x
Four sp3 hybrid
orbitals of C
-
+4
-
+
+
+
+
s orbital of 4 H atom overlap four
sp3 hybrid orbital of C atom
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On the basis of hybridization of orbital on the central atom one can explain the
geometry and bond angles of all molecule.
Sr.
No
Pure Orbitals
used for
hybridization
Hybridi-
zation
Geometry Bond
Angle
Example
1 s and p sp linear 180˚
CO2
Ag in [Ag(NH3)2]+
2 s and two p sp2 Trigonal
Planar
120˚ BF3
3
s and three
p
sp3 Tetrahedral 109˚28̎
CH4
NiCl4
Summery
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19

Hybridization-1

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