Question

Which of the following are the correct reasons for the anomalous behaviour of lithium?

• A. It has high degree of hydration
• B. Its high polarising power
• C. Exceptionally small size of its atom
• D. Exceptionally low ionisation enthalpy

Answer 1

Answer: (B), (C)

Exceptionally small size of its atom

Solution:

Lithium shows anomalous behaviour where it shows similar properties to alkaline earth metals, known as diagonal relationship.

This is due to the exceptionally small size and high charge density (polarising power) of the atom.

Due to high polarising power, lithium forms compounds with more covalent character wheareas other elements of this group forms mainly ionic compounds.

It also has high degree of hydration due to smaller size but it does not cause anomalous behaviour because ions of other member of this group is also soluble in water.

Lithium however has highest ionization enthalpy among the alkali metals.

Hence, (A) and (B) are correct options.