Question

Potassium, K, is more reactive than sodium, Na. Calcium, Ca, is less reactive than sodium. The comparative reactivity of these metals is often noted as: K > Na > Ca. Explain the reactivity differences of K, Na, Ca.

Answer 1

K is more reactive than Na because the outside electron is further away from the nucleus; thus it is easier to pull the electron away. Ca is less reactive than K because there is more positive charge holding the outside electron. Said another way, the ionization potential is lowest for K and highest for Ca with Na between.