Anomalous Behaviour Of Lithium

raja kapoor, 14 years ago

Grade:

1 Answers

Sachin Tyagi

31 Points

14 years ago

Anomalous Behaviour Of Lithium

Though lithium belongs to the alkali metals group (Group I) and has most of the characteristic properties of the metals group 1. However, it differs from the remaining members of the group in many respects. This is mainly due to the following reasons:

(i) The size of lithium atom and its ion is very small.

(ii) It has high ionization energy and least electropositive character.

(iii) The polarizing power of Li* ion is quite high due to its small size which results in the covalent character of its compounds.

(iv) It has no vacant d-orbitals in its valence shell.

Some of the important characteristics of distinction between lithium and the rest of family members are given below:

(i) Lithium is the hardest of all the alkali metals.

(ii) The melting and boiling points of lithium are much higher than those of other elements of group 1.

(iii) Lithium is less reactive as compared to other metals and it does not get tarnished readily in air.

(iv) Lithium is deliquescent and crystallizes as a hydrate, LiCl.2H₂O whereas other alkali metal chlorides do not form hydrates.

(v) Lithium bicarbonate is not obtained in the solid form while all other elements of this group form solid bicarbonate.

(vi) It forms only monoxide, Li₂O with oxygen while sodium forms peroxide, Na₂O₂ and other elements form superoxide, MO₂.

(vii) The salts of lithium have lower ionic character than salts of other alkali metals. This is because of high polarizing power of Li* ion.