Definition:
When atomic orbitals mix to form new atomic orbitals is
called hybridization.
Valence
bond theory explains bond is formed by overlapping of two half-filled valence
atomic orbitals
The electrons in overlapping get paired and confined
b/w nuclei of two atoms and electron density can be increased
Types of Covalent Bonds
There are 2 types of covalent bonds
based on pattern of overlapping
1; SIGMA BONDS
2; PI BONDS
1: SIGMA BONDS
- A sigma bond is formed by the linear or end to end overlap of orbitals
- STRONG in nature
(A) Overlapping Of 2s Orbitals
(B) By Overlapping Of Px And S
Orbitals
(C) By Overlapping Of 2 P Orbitals
2: PI BONDS
- it is formed by parallel or side to side overlap of orbitals
Characteristics;
- pi-electrons are loosely held then a pair of electrons in sigma bond
- highly reactive
- cis-trans isomers, rotation of atoms is not possible around pi-bonds
ILLUSTRATIONS AND EXAMPLES
1. H2
MOLECULES
Electronic configuration of hydrogen
is 1S1 two half filled S-orbitals of hydrogen overlaps.
CHLORINE
The electronic configuration of
chlorine is (1S2, 2S2, 2P6, 3S2, 3P5)
The valence electrons are (3S2 3P5) that
makes ———> 7 ELECTRONS, so in case of Hydrochloric
Acid we do hybridization as follows
2. HCL MOLECULE
- hydrogen = 1s1 1
- chlorine = 1s2, 2s2, 2p6, 3s2, 3p5 17
Updates:
Last update 10 Feb 2015
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