Oxidation number

[melissa_dis4K]

When finding the oxidation number do I need to do the Lewis structure to find the charge of Cl, for example in [Fe Cl(OH2)5]^+ Or how can I find the charge of chloride to be able to find the oxidation number of the central atom? Thank you!

[Jasmine Chow 1F]

Cl will always have a negative 1- charge. So say you have something that says Cl2 then the overall charge will be 2-.
In the case of [Fe Cl(OH2)5]^+
you will find the oxidation number of Fe.
So Oh2 is a neutral ligand therefore there is no charge from this molecule.
Since Cl is the only component that gives a negative charge you need a oxidation number of 2+ for Fe. This will then make the overall formal charge 1+.

Fe(II) + Cl(-1) = +1

Drawing the lewis structure helps too, most questions will ask you to draw the lewis structure with it.
When I do it, to check, I write out the charges of all the ligands and given anions. Then I determine the final oxidation number of the metal that will give me the needed overall formal charge given (in this case +1).

Hope this helps?

[Madeline Lequang 1G]

You said to draw out the lewis structure to help determine the charges for oxidation numbers, but I still don't understand how that helps.