SHAPES AND BOND ANGLES IN MOLECULES BY USING VSEPR THEORY, Delocalized in fact, this delocalization, The electrons in this pi (π) bond system do not belong to any particular carbon atom

 The electrons in this pi (π) bond system do not belong to any particular carbon atom. Each electron is free to move throughout the entire pi (π) system. It is for this reason the electrons are said to be delocalized. In fact, this delocalization gives extra stability to benzene

Delocalized in fact, this delocalization

Therefore, benzene is represented by putting a circle in a regular hexagonal shape. The structure of benzene with the ring of pi (π) electron system is very stable that even it retain its structure during substitution reactions.

SHAPES AND BOND ANGLES IN MOLECULES BY USING VSEPR THEORY:

            In covalent molecules electron pains forming the bonds are distributed in space around the central atom along definite directions. The shared electron pairs as well as the lone pair of electrons are responsible for the shape of molecules. The basic rules of valence shell electron pair repulsion (VSEPR) theory which helps to explain shapes and bond angles in molecules are given below:

(1)       Shape of a molecule could be explained on the basis of number of electron pairs present in the outer most shell of the central atom.

(2)       Each electron pair tries to separate itself as much as possible from other electron pairs sp as to minimize repulsion between them.

(3)       Lone pair of electrons occupy more space than bonding pairs. The repulsion between electronic pairs in valence shell, decreases in the following order, lone pair-lone pair > lone pair-bond pair> bond pair-bond pair.

(4)       Electro negativity is the relative power of an atom to attract shared pair of electrons more toward itself in a covalent bond. Therefore, in a molecule bond pair of electrons with more electro negativity element move away from the central atom and due to long distance repulsion between bond pairs decreases, hence they tend to occupy more space. Therefore, the bond angles increases.

(5)       Lone pair of electrons have influence on the shape and bond angle of molecule but actually in the description of the shape and bond angles of molecules only bond pairs are included.