Quick question about Aluminium ? How to find its oxidation state ?

[nukeman]

Homework Statement

I am struggling a bit with naming compounds.

Al2(Cr2O7)3

Now, I know its aluminum dichromate, and the way to find this was KNOWING the oxidation state of Al being +3 - How am I suppose to know that? How do you find that out when all you have is a basic periodic table?

Homework Equations

The Attempt at a Solution

 

[nukeman]

Anyone :)

 

[Infinitum]

You had the same post in the Chemistry section...and as the topic refers to chemistry...

https://www.physicsforums.com/showthread.php?t=604327