so i decided today that i would just get myself familiar with chemistry again  so i am starting out at the basics…
i was doing a problem, and just wanted to see if someone may review it for me:
infer the simplest chemical formula for potassium copper fluoride, which has the analysis by weight:
K â€“ 35.91%
Cu â€“ 29.19%
F â€“ 34.90%
KCu2F
Key for below:
Element  Atomic Ratio, Atomic Relative, Relative Weight, and Weight Percent
Potassium  1, 39.098g, 1.089 (does this have a unit of measurement, like mole or something?), 35.91%
Copper  2, 63.546g, 2.177, 29.19%
Fluoride  1, 18.998g, 0.544, 34.90%
I came up with relative weight by dividing the atomic relative by the weight percent.
Then, to come up with the atomic ratio for each element I divided 1.089 (K’s relative weight) by 2.177 (Cu’s relative weight) which is about .5  therefore (assuming this is a stoichiometric compound)
1 K

2 Cu
And did the same thing for finding F’s atomic ratio  but I divided 2.177 (Cu) and 0.544 (F)
which is about 2  so,
1 Cu

1 F
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Since I have not had ANY chemistry or exposure to it since 2001  I am not tooooo sure at all about all this LOL but figure to go through some material and get the basics back prior to the semester cannot hurt.
I know that when I did this same problem for Aluminum Oxide (analysis was given as 53% aluminum and 47% oxygen by weight) I did it right… at least I think.
Key for below:
Element  Atomic Ratio, Atomic Relative, Relative Weight, and Weight Percent
Aluminum  2, 26.98g, 1.9161, 52.92%
Oxygen  3, 16.00g, 2.943, 47.08%
Relative weights obtained the same way, the Weight Percent divided by the Atomic Relative.
Since the ratio between Al and O is .66 (1.9161/2.943), there are 2 Al atoms and 3 O atoms in Aluminum Oxide.
I also noticed that if i flip the order in which I try and find the atomic ratio, it ends up the same. 2.943/1.9161 = 1.54 (since this is about whole numbers, we cannot have .4 of an atom, i round up to 1.5, if it were 1.56 then would i round to 1.6??) which would be 3 over 2 …
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So I guess I have 5 questions here.
 Does the relative weight, that is calculated from the ratio of weight percent and atomic relative, have a unit of measurement?
 How do I figure out the simplest Chemical Formula, from just the percentage of each element by weight, when there are more than TWO atoms in the compound?
 When figuring out the atomic ratio, is it kosher to flip which element’s relative weight you put first? (it seems okay to me, but not really sure if there can ever be an exception to the rule)
 Since most chemical compounds are stoichiometric compounds, what are the cases of nonstoichiometric compounds I need to worry about?
 If I understand the process right, metals that are used as catalysts in the oxidation process temporarily create nonstoichiometric compounds (as the vacancy of oxygen is only temporary and replaced by O2)?
Thanks everyone!