The elements of second period resemble in many respect to those elements of third period which are diagonally opposite to them (diagonal relation)
Diagonally related elements have nearly the same value of
(a) electronegativity
(b) polarising power
(c) Ionic potential $\left[\frac{\text { ionic charge }}{\text { (atomic radius) }^{2}}\right]$
Anomalous behavior of an element mentions the deviation of the properties and behavior of an element from its usual or normal behavior.
Lithium is harder than other metals of the particular group.
In comparison to other metals, has higher melting and boiling point.
Least reactive in nature.
The strongest reducing agent in nature.
Unlike other metals, LiCl is aqueous and exists as LiCl2H2
Li+ ion polarizes water molecules more readily than other alkali metals of the particular group and hence the lithium salts attract the water molecules and it exists as water of crystallization (2H2O). As the polarizing power diminishes with the rising size of the ions the other alkali metal ions usually form anhydrous salts.
Lithium does not form ethynide on reacting with Ethyne.
Heating lithium nitrate results in the production of lithium oxide, Li2
4LiNO3 --> 2Li2O + 4NO2 + O2
Lithium nitrate Lithium oxide
Heating nitrates of other alkali metals manifest in the decomposition of the nitrate leading to the production of their corresponding nitrite.
