Question

In what ways lithium shows similarities to magnesium in its chemical behaviour?

Answer 1

Chemical similarities between $Li$ and $Mg$:
(1) Their reaction with cold water is slow.
(2) The solubility of the oxides of $Li$ and $Mg$ in water is low. At high temperature, the hydroxides decompose.
$2LiOH\stackrel{Heat}{\to }L{i}_{2}O+H_{2}O$
$Mg(OH{)}_2\stackrel{Heat}{\to }MgO+H_{2}O$.
(3) They form nitrides by reaction with nitrogen.
$6Li+N_2\stackrel{heat}{\to }2L{i}_{3}N$
$3Mg+N_2\stackrel{heat}{\to }M{g}_3{N}_2$
(4) They do not form peroxides or superoxies.
(5) They form covalent carbonates which decompose on heating.
$L{i}_{2}C{O}_3\stackrel{heat}{\to }L{i}_{2}O+C{O}_2$
$MgC{O}_3\stackrel{heat}{\to }MgO+C{O}_2$
(6) They do not form solid bicarbonates.
(7) Their covalent chlorides are soluble in ethanol.
(8) Their chlorides are deliquescent and crystallize from aqueous solution as hydrates such as $LiC{l}_2.2H_{2}O$ and $MgC{l}_2.8H_{2}O$