yes aluminum is less reactive than magnesium it is less reactive because as you read left to right on the periodic table the element became less reactive because they get more electrons on their valence shellAluminum is exactly as reactive as it is in the reactivity seriesHowever, when aluminum reacts, with oxygen for instance, a thin layer of aluminum oxide builds up on the outside of the aluminum metalThis prevents more oxygen from reaching unreacted aluminum metalThis prevents the reaction from proceeding further, thus effectively protecting the aluminum metal from further reaction.
