Oxidation Numbers 17.29

[Isaac Eyler 1E]

17.29 asks us to name the complex (which I understand) and then to determine the oxidation number of the metal. The solutions manual gives a formula for finding the oxidation number of the metal:

(# of metal atoms)(oxidation number of the metal) + ∑(# of each ligand)(charge of each ligand) = charge of the ion

First, is there an easier/quicker way to find the oxidation of the metal, or is plugging the numbers into the formula the only way?

Second, how do you find the charge of each ligand? With the chemical formula's given in, for example, 17.29d) [Co(SO4)(NH3)5]+
how do I know that the charge of SO4 is -2 like the solutions manual says? Because in 17.29a-c, sometimes the ligand charge is -1 or 0.

[Ashley Davis 1I]

I think for the ligands we're meant to know what charge they have? I'm not sure if we need to memorize polyatomic ions... And as far as I know I don't know an easier way to compute it :/

[Jana Sun 1I]

I agree with the post above; I think we're just supposed to memorize the charges of the ligands. As for the formula for calculating the oxidation number of the metal, I personally don't write everything out in the formula. I just know that the charges of the molecule should add up to the overall charge, so I use the same process that the equation uses but just shorten it a bit (picture: https://mail.google.com/mail/u/0/?ui=2& ... c2e050_0.1).