Aluminum Sulfate Al2(SO4)3

How many atoms of each element are in 4 moleculesof this compound? I got Al = 2, S = 3, O = 7, and Al2(SO4)3 = 1
I'm guessing it's wrong,

And
What is the oxidation state(number)of the positively charged ion
I forgot how to find the oxidation number

Question

Aluminum Sulfate Al2(SO4)3

How many atoms of each element are in 4 moleculesof this compound? I got Al = 2, S = 3, O = 7, and Al2(SO4)3 = 1
I'm guessing it's wrong, 

And
What is the oxidation state(number)of the positively charged ion
I forgot how to find the oxidation number

anonymous · Answer

on the first part, the wording is "4 molecules" not one molecule, although i think aluminum(III) sulfate is an ionic solid so these are more like formula units than molecules.

anonymous · Answer

THanks :) but i'm still confused about the oxidation part

anonymous · Answer

what does your book say about the oxidation number of a charged atom, such as the aluminum ion?