Define how can we introduce partial covalent character in ionic compounds
Answers
Due to electonegativity defference of bonded atom covalent bond devolope ionic character the ionic bond also develops covalent character as described below:
When positive ion and negative ion come close to each other , positive ion attract the electron cloud of negative ion towards itself. The anion undergoes some distortion. The electron cloud of negative ion gets polarised and electron density is pulled in between the nuclei of the two ions The build up of electron density in between the two nuclei is shown in Fig.1 The ionic bond does not remain 100% ionic but develops some covalent character.
Polarising power :
• The power of cation to cause distortion in the electron cloud of anion is referred to as its polarising power.
Polarisability :
• The ability of anion to undergo distortion is called polarisability .
• The extent of covalent character in ionic bond depents on the polarising power of cation and polarisability of anion which are decided on the basis of set of rules called Fajan rules.
These are described as follows:
1. Smaller the size of cation, larger will be its polarizing power.
2. Larger the size of anion, higher will be its polarisability.
Explanation:
The electron cloud of negative ion gets polarised and electron density is pulled in between the nuclei of the two ions The build up of electron density in between the two nuclei is shown in Fig. 1 The ionic bond does not remain 100% ionic but develops some covalent character.