Lithium resembles magnesium mainly due to same charge/radius ratio or polarizing power. The main points of similarity are:
(a) Both \(\mathrm{LiOH}\) and \(\mathrm{Mg}(\mathrm{OH})_2\) are weak bases.
(b) Both form ionic nitrides when heated in atmosphere of nitrogen, \(\mathrm{Li}_3 \mathrm{~N}\) and \(\mathrm{Mg}_3 \mathrm{~N}_2\).
(c) The hydroxides and carbonates of both of them decompose on heating.
(d) Both \(\mathrm{Li}\) and \(\mathrm{Mg}\) do not form solid bicarbonates.
(e) \(\mathrm{Li}\) and \(\mathrm{Mg}\) do not form peroxides and super oxides.
(f) Both \(\mathrm{Li}\) and \(\mathrm{Mg}\) nitrates decompose on heating producing \(\mathrm{NO}_2\).
\(4 \mathrm{LiNO}_3 \longrightarrow 2 \mathrm{Li}_2 \mathrm{O}+4 \mathrm{NO}_2+\mathrm{O}_2\)
\(2 \mathrm{Mg}\left(\mathrm{NO}_3\right)_2 \longrightarrow 2 \mathrm{MgO}+4 \mathrm{NO}_2+\mathrm{O}_2\)
(g) The hydroxides, carbonates and fluorides of lithium and magnesium are sparingly soluble in water.
(h) \(\mathrm{LiCl}\) and \(\mathrm{MgCl}_2\) are highly soluble in ethanol.