Question

the Alkali metal,the metal least ionisation enthalpy is

Answer 1

lithium is the smallest hence it has least ionization potential

Answer 2

Answer:

Trends in atomic radii :

(1) Alkali metals have the largest atomic radii in their respective periods.

(2) In the group, as atomic number increases the valence electron enters a new shell hence atomic radii increase, from top to bottom.

(3) Thus, atomic radii increase in the order of Li < Na < K < Rb < Cs < Fr. Trends in ionisation enthalpy:

(1) Ionisation enthalpies of alkali metals are low in their respective periods due to their large atomic radii.

(2) It decreases down the group from lithium to caesium due to increase in atomic radii.

Among the alkali metals, lithium has the highest ionisation enthalpy.