Is there a chemist in the house?

[Aster]

What's the difference between alum and aluminum?

[Jane]

Alum isn't a specific chemical name, it's sort of like "nitrate" or "hydrate" in that it specifies a chemical group that is attached to something else. And, it's an oldie name, not a standard one, so it isn't as descriptive as it might be.

Cake alum, the kind in the grocery store is:
Aluminum sulfate Al2(SO4)3

Aluminum is a metal, aluminum sulfate is aluminum bonded with sulfate groups. The two groups should disassociate in water, adding ions of aluminum and sulfate to the solution.

There are other types of alum too.

[Aster]

So, when i use baking powder (that contains cake alum doesnt it?), i'm going to end up with aluminum in my food because of the chemical reaction that happens? !!

How about potassium alum? (crystal deodorant sticks are made out of potassium alum) Does that disassociate into ions of aluminum and potassium?

[Jane]

Potassium alum is KAl(SO4)2·12(H2O). It does have aluminum in it. The makers of the deodorant claim that this molecule doesn't separate into potassium and aluminum and the sulfate ion. They claim it separates into the potassium and the aluminum sulfate, never leaving the aluminum free to do anything to you. I don't have any concrete reason to doubt that, but it is ringing bells for me as false.
On a related note, personally, I don't believe aluminum is bad for you in normal amounts. I suspect it's the other way around. Aluminum is found in abnormal cells because abnormal cells grab aluminum, not because the cells are abnormal due to aluminum. Then again, I don't wear deodorant or antipersperant either.

As far as baking powder, it depends on what you use. I make my own from 1/2 soda and 1/2 cream of tartar. It has no aluminum. Some commercial ones have aluminum and some don't. A site that talks about the different types and the different uses:
http://users.rcn.com/sue.interport/food/bakgsoda.html

[Aster]

Apricot, this information is very helpful to me. Thank you for taking the time to answer my questions.