Multiple choice general knowledge science & technology How many electrons are found in the outermost shell of aluminum (Al, atomic number 13)? 2 3 5 8 Reveal answer Fill a bubble to check yourself B Correct answer Explanation Aluminum (atomic number 13) has electron configuration 2-8-3. The inner shells hold 2 and 8 electrons, leaving 3 valence electrons in the outermost shell. This matches aluminum's position in Group 13 of the periodic table.