valence bond theory
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Answer:
In chemistry, valence bond theory is one of the two basic theories, along with molecular orbital theory, that were developed to use the methods of quantum mechanics to explain chemical bonding.
Explanation: Valence Bond Theory also written as VBT in short form, is one of the two theories other than molecular orbital theory which must be studied to understand Chemical bonding precisely. It was proposed by Hietler and London to understand "The shape of the covalent molecules, their bond lengths and bond angles too." It was extended by Pauling and Slater to make the directional nature of covalent bonds more clear. A Covalent bond is formed between electrons of different atoms, the electrons present in the atoms must possess opposite spins, these electrons of different atoms will overlap each other and thus a covalent bond is formed. Another type of chemical bonding, Dative Bond, that takes place between atoms which has unpaired electrons and a vacant orbital. There are sub-divisions to Covalent bond too.
* Sigma Bond - The type of covalent bonding whose electron cloud is concentrated axially, i.e. between the internuclear axis and which has a Cylindrical symmetry is known as Sigma Bond. The linear overlapping results in the formation of a Sigma Bond.
*Pi Bond - The type of covalent bond which is formed between electrons of atoms which are already bounded by a sigma bond and whose electron cloud is present at both the sides of its internuclear axis. Lateral overlapping results in the formation of Pi Bond.
Notes to remember.
* A pi bond is formed only after a sigma bond is formed.
* A Sigma Bond is stronger than a pi bond.
* A double bond is a combination of one sigma bond and one pie bonds and a triple bond is a combination of one sigma bond and two pi bonds.
* The order of bonding intensity is as follows
p-p > s-p > s-s
Now, you must be wondering what is all this s's and p's, An atom has electrons revolving around the nucleus in different orbits, and the sub divisions of orbits are known as orbitals. S and P are orbitals.
Just in case you weren't familiar with Orbital's, if you were then cool!
*At the time when atoms come closer to each other to form a bond then there overlapping can be negative, positive and even zero based on sign and direction of orientation.
Well, I think this much is enough because after learning this we have to learn about the types of hybridization's and what is Hybridization which is pretty vast.
But, just for a rough idea what is hybridization is the process where electrons are intermixed and then again re-arranged into equal number of hybrid orbitals. The types of hybridization is as follows
* SP type.
* SP^2 type
* SP^3 type
* DSP^2 type
* SP^3D^2 type
* SP^3D^3 type.
Thank you, I think and hope this was helpful.