Why are alkali metals considered to be powerful reducing agents?

Reducing agent

• A substance that loses electrons to other substances in a redox reaction and gets oxidized to a higher valency state is called a reducing agent.

Alkali metals

• Lithium, sodium, potassium, rubidium, caesium, and francium. They are collectively known as alkali metals.
• The general electronic configuration of alkali metals is $\mathrm{noble}\mathrm{gas}\left[{\mathrm{ns}}^1\right]$.
• Due to low ionization potential and having the smallest nuclear charge, they can easily lose an electron.

Valency of alkali metals

• Only one electron is present in the valence shell of alkali metals.
• They rapidly lose an electron, resulting in monovalent ${\mathrm{M}}^{+}$ ions.

Example

• Lithium $\left(1{\mathrm{s}}^{2}2{\mathrm{s}}^1\right)$losses one electron easily to achieve the nearest noble-gas configuration$\left(1{\mathrm{s}}^2\right)$ and become more stable.
• $\mathrm{Li}\to {\mathrm{Li}}^{+}+{\mathrm{e}}^{-}$.

Hence, alkali metals are considered to be powerful reducing agents due to their low ionization potential and having the smallest nuclear charge, they can easily lose an electron.