Describe fajan's rule.

Explanation

(i) He ability of a cation to polarise an anion is called its polarising ability and the tendene of an anion to get polarised is called its polarisibility. The extent of polarisation in an ionie compound is given by the Fajans rule.
(ii) he ability of a cation to polarise an anion is called its polarising ability and the tendeney of an anion to get polarised is called its polarisibility. The extent of polarisation in an ionie compound is given by the Fajans rule cloud of the anion. Similarly higher the magnitude of negative charge on anion, greater is its polarisability. For example, `Na^(+) lt Mg^(2+) lt Al^(3+),` the covalent character also follows the order:
`NaCl lt MgCl_(2)lt AlCl_(3)`
(iii) The smaller cation and larger anion show greater covalent character due to the greater extent of polarisation. e.g.. LiCI is more covalent than NaCI.
Cation having `ns^(2)np^(6)nd^(10)` configuration shows greater polarising power than the cations with `ns^(2)np^(6)` configuration. e.g.. CuCl is more covalent than NaCl.