Polarization and Fajan's Rule

State the Fajan's rule.

Fajans' rule states that a compound with low positive charge, large cation and small anion has covalent bond where as a compound with high positive charge, small cation and large anion are ionic bonded.

Explain why cation are smaller and anions larger in radii than their parent atoms?

The size of cation is smaller than its parent atom. Why?

Amongst $\mathrm{LiCl}, \mathrm{RbCl}, {\mathrm{BeCl}}_2 \text{and} {\mathrm{MgCl}}_2$, the compounds with the greatest and the least ionic character, respectively, are.

The most polarisable ion among the following is.

Choose the correct statement with reference to water and hydrogen peroxide. 

Incorrect option among the following is :

When a $300 \mathrm{m}\mathrm{m}$ long tube filled with $60 \mathrm{c}\mathrm{c}$ of sugar solution produces an optical rotation of $9^o,$ find the quantity of sugar in the solution ( $\alpha$ for sugar is $6^o{\mathrm{m}}^2/\mathrm{k}\mathrm{g}$ ).

Polarizing action of $\mathrm{C}{\mathrm{d}}^{2+}$ on anions is stronger than that of $\mathrm{C}{\mathrm{a}}^{2+}$ because

When a neutral atom is converted to the anion its

In the ionic bond, a cation tend to polarize the electron cloud of the anion by pulling electron density towards itself. This causes development of covalent character in ionic bond because the electron density gets localized in between the nuclei. The tendency of cation to bring about the polarization of anion is expressed as its polarizing power. The ability of ion to undergo polarization is called its polarizability. The polarizing power of cation and polarizability of anion are decided on the basis of Fajan rules as given below:

i) The smaller the cation, the higher is its polarizing power.

ii) Cations with pseudo noble gas configuration $\left(\mathrm{n}{\mathrm{s}}^2\mathrm{n}{\mathrm{p}}^6\mathrm{n}{\mathrm{d}}^{10}\right)$ having relatively high polarizing power than those with noble gas configuration $\left(\mathrm{n}{\mathrm{s}}^2\mathrm{n}{\mathrm{p}}^6\right)$ .

iii) The larger the size of the anion, the higher is its polarizability.





The ionic conductance of which of the following is the highest?

Which of the following is/are correct?

The decreasing order of size of isoelectronic series ${\mathrm{K}}^{+},\mathrm{ }{\mathrm{C}\mathrm{a}}^{2+},\mathrm{ }{\mathrm{C}\mathrm{l}}^{-}$ and ${\mathrm{S}}^{2–}$ is :

The ion having biggest size is

Which of the following is/are correct?

Which of the following represents the incorrect order of properties?

Which of the following has a high polarizing power?

The most favourable conditions for the formation of ionic bonds are:

Which of the following polyhalide ion is most stable ?