Explain why sodium is less reactive than potassium.

The ionization enthalpy of potassium is lower (496  kJ/mol) than that of sodium (520 kJ/mol). As a result, the ease with which K can lose an electron is greater than the ease with which Na can lose an electron.

As a result, sodium has a lower reactivity than potassium.

Potassium's standard reduction potential (-2.925 V) is lower than that of sodium (-2.714 V). This also indicates that sodium has a lower reactivity than potassium.

Final Answer: The reactivity of alkali metals is due to their large size and low ionization enthalpy, which eases the release of alkali metals' outermost electrons. As we move down the group, the size of the metal grows and the ionization enthalpy decreases. Because of this, sodium is less reactive than potassium.