Question

The reducing capacity of alkali metals increases as we move down the group. Explain.

Answer 1

The alkali metals have low values of reduction potential and therefore have a strong tendency to lose electrons and act as good reducing agents. The reducing character increases from sodium to caesium. However lithium is the strongest reducing agent.

The alkali metals have a low value of ionization energy which decreases down the group and so can easily lose their valence electron and thus act as good reducing agents.

The alkaline earth metals are weaker reducing agents than the alkali metals. Like alkali metals, their reducing character also increases down the group. This is due to the reason that the alkaline earth metals have greater tendency to lose electrons so, they act as reducing agent but since their I.E. are higher and their electrode potentials are less negative than the corresponding alkali metals, therefore alkaline earth metals are weaker reducing agents than alkali metals. The sulphates are stable to heat whereas the carbonates decompose to give MO and $C{O}_2$, the temperature of decomposition increasing from Mg to Ba. $BeC{O}_3$ is kept in the atmosphere of $C{O}_2$ to prevent its decomposition.
$\begin{array}{ccccc}BeC{O}_3& MgC{O}_3& CaC{O}_3& SrC{O}_3& BaC{O}_3\\ {100}^{\circ }C& {540}^{\circ }C& {900}^{\circ }C& {1290}^{\circ }C& {1360}^{\circ }C\end{array}$