Chemical bonding shape of the molecule

1. Dr. M.S.M. Badhusha
Assistant Professor of Chemistry
&
Additional Research Coordinator
Sadakathullah Appa College, Tirunelveli.
CHEMICAL BONDING Shape of
the Molecule

2. Valence Shell Electron Pair Repulsive
Theory (VSEPR Theory)
 Valence shell electron involve in bonding
 Species whose Central atom is surrounding by σbps
only ( BeCl2, CH4)
 Species whose Central atom is surrounding by σbps
and lps ( NH3, H2O)
 Species whose Central atom is surrounding by σbps
and bps ( CO2, HCN)
 Species whose Central atom is surrounding by
σbps, lps and bps ( SO2, ClO3-)

3. BeCl2 Linear
• 2 atoms attached to center atom
• 0 unshared pairs (lone pairs)
• Bond angle = 180o
• Type: AX2
• Ex. : CO2 BeCl2,

4. BF3 Trigonal Planar
• 3 atoms attached to center atom
• 0 lone pairs
• Bond angle = 120o
• Type: AX3
• Ex. : BF3

5. CH4 Tetrahedral
• 4 atoms attached to center atom
• 0 lone pairs
• Bond angle = 109.28o
• Type: AX4
• Ex. : CH4
CCl4

6. Trigonal Bipyramidal
• 5 atoms attached to center atom
• 0 lone pairs
• Bond angle =
– equatorial -> 120o
– axial -> 90o
• Type: AX5
• Ex. : PF5

7. Octahedral
• 6 atoms attached to center atom
• 0 lone pairs
• Bond angle = 90o
• Type: AX6
• Ex. : SF6

8. Trigonal Pyramidal
• 3 atoms attached to center atom
• 1 lone pair
• Bond angle = 107o
• Type: AX3E
• Ex. : NH3

9. Bent – V shape
• 2 atoms attached to center atom
• 2 lone pairs
• Bond angle = 104.5o
• Type: AX2E2
• Ex. : H2O

10. VSEPR Geometries

11. Hybridization
The merging of orbitals
•Merging orbitals must all be half filled
•No orbitals are “lost” due to merging – if
you blend one s orbital and one p orbital you
will end up with TWO hybrid orbitals!

12. Structure of Methane
tetrahedral
bond angles = 109.5°
bond distances = 110 pm
but structure seems inconsistent with
electron configuration of carbon

13. Electron configuration of carbon
only two unpaired
electrons
should form s
bonds to only two
hydrogen atoms
bonds should be
at right angles to
one another
2s
2p

14. 2s
2p
sp3 Orbital Hybridization
Promote an electron from the 2s
to the 2p orbital

15. 2s
2p 2p
2s
sp3 Orbital Hybridization

16. 2p
2s
sp3 Orbital Hybridization
Mix together (hybridize) the 2s
orbital and the three 2p orbitals

17. 2p
2s
sp3 Orbital Hybridization
4 equivalent half-filled
orbitals are consistent
with four bonds and
tetrahedral geometry
2 sp3

18. sp2 Hybridization in BF3
_ _ _
↓ 2p1 Unhybridized Boron
2s2
For BF3, 3 hybrid orbitals are needed, so 3 atomic
orbitals are required as follows: (s + p + p) = sp2
_ _ _
sp2 sp2 sp2 Hybridized Boron

19. 3 sp2 orbitals needed
to form 3 sigma bonds

20. sp Hybridization in BeCl2
_ _ _
 ↓ 2p Unhybridized Be
2s2
 For BeCl2, 2 hybrid orbitals are needed, so 2 atomic
orbitals are required as follows: (s + p ) = sp
_ _
sp sp Hybridized Be

22. SP3d Hybridization
 sp3d hybridization involves the mixing of 3p and 1d orbital to
form 5 sp3d hybridized orbitals of equal energy. They have
trigonal bipyramidal geometry.
 Three hybrid orbitals lie in the horizontal plane inclined at an
angle of 120° to each other known as the equatorial orbitals.
 The remaining two orbitals lie in the vertical plane at 90
degrees plane of the equatorial orbitals known as axial orbitals.
 Example: PCl5

23. sp3d2 Hybridization
 sp3d2 hybridization has 1s, 3p and 2d orbitals, that
undergo intermixing to form 6 identical sp3d2 hybrid
orbitals.
 These 6 orbitals are directed towards the corners of an
octahedron.
 They are inclined at an angle of 90 degrees to one
another.
 Example: SF6