Question

Which alkali metal ion has the maximum polarizing power? Explain.

Answer 1

When any ion can distort an oppositely charged ion, then this ability is known as polarizing power. Alkali metal ion means the ion belongs from group 1 of the periodic table. The element that has the maximum polarizing power has atomic number 3 and belongs to period 2.

Complete answer:
Polarizing power is a property that is shown by small ions. When the cation has the ability to distort an anion, then this ability is known as polarizing power. When the anion can be easily polarized by the cation then it is known as polarizability.
Alkali metal ion means the ion belongs from group 1 of the periodic table. The element that has the maximum polarizing power has atomic number 3 and belongs to period 2. So, the element of the alkali metals is lithium. Therefore, lithium ion ($L{{i}^{+}}$) has the highest polarizing power.
This polarizing power of the lithium is explained by the size and charge of the ion, as we know that the size of the lithium in the alkali metal ions is the smallest, due to which the ratio of charge and size is very high.
So, due to the high charge to size ratio, the lithium ion can attract the electron cloud of the anion like a halide ion towards itself.
Therefore, the lithium ion ($L{{i}^{+}}$) is the answer of an alkali metal ion that has the maximum polarizing power.

Note:
We know that when the cation and anion react with each other, then there is the formation of an ionic compound, but due to the high polarizing power of lithium ion, it mostly forms covalent compounds.