Explain why is $sodium$ less reactive than $potassium$?

(N/A) The reactivity of alkali metals increases down the group as the ionization enthalpy decreases.
$Sodium$ $(Na)$ is in the $3rd$ period,while $potassium$ $(K)$ is in the $4th$ period.
Due to the larger atomic size of $potassium$,the valence electron is further away from the nucleus compared to $sodium$.
Consequently,the force of attraction between the nucleus and the valence electron is weaker in $potassium$,making it easier to lose the electron.
Therefore,$potassium$ has a lower ionization enthalpy than $sodium$,which makes $potassium$ more reactive than $sodium$.