what is the formula for aluminum chloride
Â· just now. The formula for aluminium chloride is AlCl3. This is because aluminium is a 3rd family element, and thus has 3 valence electrons. chlorine is a 7th family element and thus has 7 valence electrons. When molecules form, generally they form to get 0 or 8 valence electrons. So, aluminium gives 3 electrons to the chlorine atoms and goes to 0, and each chlorine atom gets 1, bringing each to 8.