What happens when aluminum fills its valence shell?
a. three electrons are lost creating al+3
b. three electrons are gained creating al+3
c. three electrons are gained creating al-3
d. three electrons are gained creating al-3

Aluminum is a metal and its oxidation state is +3. That means that it may lose three electrons and form cation Al +3. So the correct answer is option A. threee electrons are lost creating Al +3.

You can base your answer in the fact is in the group 13, that means that it has 3 electrons in its valence shell. Those are the three electrons that it can lose to form Al +3.

Also, you can search for the atomic number and do its electron configuration.

Z Al = 13 => 1s2 2s2 2p6 3s2 3p1. So, the electrons 3s2 3p1 are the three electrons that it can lose to form Al +3.