Question

"Alkali metals are good reducing agents as in case of alkali metals, outer ns-electron is very well shielded by the inner electrons."
Answer whether the above statement is true or false.
If true enter 1, else enter 0.

Answer 1

Hint: Major factors that affect the magnitude of the shielding effect seen in the atoms are the number of inner-shell(s) electrons present and the type of the orbital occupied by the electrons.

Complete step by step solution:
The decrease in the attractive force exerted by the nucleus on the valence- shell electron, due to the presence of the electrons lying between the nucleus and valence-shell electrons, is called shielding effect.

In the case of alkali metals, as we move down the group, the atomic radius of alkali metals increases from Li to Cs as the atoms become larger which leads to low first ionization energy. Due to this increase in size the outer ns-electron is very well shielded by the inner electrons and the effective force exerted by the nucleus on the only valence shell electron decreases, which is also called as shielding effect. Shielding effect also increases as we go down the group. This results in the increase in the ability of releasing that electron. Therefore, an overwhelming tendency to form ionic compounds having a +1 charge. Thus, act as good reducing agents.
Therefore, the statement is true.

Note: Unexpectedly, the strongest reductant is lithium, and the weakest is sodium, because Li+ is much smaller than the other alkali metal cations. Though lithium metal is the strongest reductant in aqueous solution due to its high hydration energy.