CHEMISTRY : CHEMISTRY Chemical Bonding
What is Chemical Bonding? : What is Chemical Bonding? A chemical bond is a force of attraction that binds the atoms together. Molecules have lesser energy than atoms, so they are more stable.
On the basis of wave mechanics, two theories are proposed to explain chemical bonding
On the basis of wave mechanics, two theories are proposed to explain chemical bonding : On the basis of wave mechanics, two theories are proposed to explain chemical bonding 1. Valance Bond Theory (V.B.T)
2. Molecular Orbital Theory (M.O.T)
Valance Bond Theory (V.B.T) : Valance Bond Theory (V.B.T) Main Features:
i). A covalent bond is formed by the overlap of half-filled atomic orbitals of different atoms.
ii). The strength of bond depends upon on extend of overlap and energy released during overlapping.
Defects: : Defects: This theory could not explain para magnetic behaviour of O2 and bonding in electron deficient compounds
Para Magnetic behaviour : Para Magnetic behaviour
Electron Deficient Compound : Electron Deficient Compound Compounds that contain at least one atom (other than H) that shares fewer than eight electrons
Molecular Orbital Theory (M.O.T) : Molecular Orbital Theory (M.O.T) This theory was proposed by Hund and Mulliken.
According to MOT
In molecules, electrons are present in a special type of orbitals called molecular orbitals.
They are characterised by a set of quantum numbers.
They are formed by the combination of atomic orbitals of nearly same energy.
Are associated with the nuclei of all the atoms constituting the molecules.
No. of molecular orbitals formed is equal to the no. of atomic orbitals combined.
Are filled in the increasing order of energies.
Also obey Pauli’s exclusion principle and Hund’s rules.