Final answer:
Aluminum has three valence electrons and is quite reactive. It can lose all three electrons to form an Al3+ cation, resulting in compounds with a 3+ oxidation state. Its reactivity is comparable to, but can require more energy than, metals with only one or two valence electrons.
Step-by-step explanation:
The reactivity of aluminum compared to other metals with fewer valence electrons can be understood based on its tendency to lose these electrons when reacting. Metals with one or two valence electrons, such as the alkali metals like lithium and sodium, tend to be more reactive because achieving a stable electronic configuration by losing one or two electrons requires less energy. In contrast, aluminum, with three valence electrons, also has high reactivity due to both the ability to lose all three valence electrons to form a stable cation, Al3+, and its prevalence in the Earth's crust making it readily available for reactions.
The electron configuration of an aluminum atom is 1s22s22p63s23p1, and when it reacts, it often uses all three of its valence electrons, resulting in an oxidation state of 3+. Although some compounds formed by aluminum are covalent, others, like AlF3 and Al2(SO4)3, are ionic. An example reaction with aluminum is: 2Al(s) + 2NaOH(aq) + 6H2O(l) which generates hydrogen gas and showcases the reactivity of aluminum both with acids and bases.