Partial ionic character of covalent bond
1. When two atoms of different elements are linked by a covalent bond
2. The shared electrons are not attracted equally by the two nuclei of bonding atoms.
3. Due to unequal distribution of electron cloud, one end of the molecule acquire partial positive charge and the other end acquires equal partial negative charge.
4. The polarity of bond gives partial ionic character.
5. The percentage of partial ionic character depends upon the difference of E.N. Of two atoms join with each other through a covalent bond.
Orbital Overlap Concept
1. In the formation of hydrogen molecule, there is a minimum energy state when two hydrogen atoms are so near that their atomic orbitals undergo partial interpenetration.
2. This partial merging of atomic orbitals is called overlapping of atomic orbitals which results in the pairing of electrons.
3. The extent of overlap decides the strength of a covalent bond.
4. In general, greater the overlap the stronger is the bond formed between two atoms.
5. The valence bond theory explains the shape, and hybridisation of atomic orbitals.