how do you properly calculate transition metal oxidation numbers?

[mikexima]

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Is there any real method to properly calculate transition metal ionic charges without memorizing them? Like for example we all know group 1 elements produce +1, group 2 produces +2, halogens produce -1. I understand that Iron first gets rid of its two 4S electrons to produce a +2 and then another one to form a +3 and gain itself a stable half filled 3d subshell. but what about elements like Copper? how is it that copper produces +1 & +2?

 

[Avery07]

It's pretty simple to learn.

Your transition metal will always be surrounded by elements that you know what charge they want to form.

1A = 1+
2A = 2+
3A = 3+
4A = --
5A = 3-
6A = 2-
7A = 1-

So you take these atoms, add up all the charges they want to form, and then find that opposite charge for your transition element.

Example:

FeCl2

You know that chlorine will form a 1- charge. Take this times 2 as you have two chlorine atoms. So you have a total charge of 2-. You want the opposite charge for your iron atom; this gives us Iron 2+ or Iron II.

Hope this helps. 👍

 

[mikexima]

Well my question was not directed towards finding the transition metal oxidation numbers in a molecule, but rather the likely charges the element would produce to become a cation.

For example, If you were to come across a question that straight out asked to list all the possible cations for gold, how would you go about it? Its pretty easy to calculate its oxidation in a molecule. but there is really no rule of thumb for transition metals the way there is for elements in group 1-8.

I ran into a practice problem that said Iron bonds to element X to form FeX and Fe2X3. Find out what molecules Cu would make with element X. without knowing its possible cations, its too hard. know what im saying?

 

[SoulPower]

Just as a reference, I have taken the DAT twice and done a ton of practice problems and have never seen a question like the one you described. Cause that would seem almost impossible unless you knew what element X was.