## Determining Oxidation Numbers

Isabella Shahmirza 2H
Posts: 30
Joined: Fri Sep 25, 2015 3:00 am

### Determining Oxidation Numbers

How do you determine the oxidation states for the ligands and transition metals? For example, in [Co(NH3)4(NO2)Cl]Cl, I know that NO2 has a negative one charge, but how do we know that cobalt has a 3+ charge?

Mir Raza 3D
Posts: 19
Joined: Fri Sep 25, 2015 3:00 am

### Re: Determining Oxidation Numbers

Add up all negative charges and then give the metal (which in this case is Co) a positive charge that will cancel out the negative charges. So for example NO2 has a -1 charge, there are 2 Chlorines (Cl) which each have a -1 charge. NH3 has no charge so we don't need to worry about it. By adding the charges, (-1) + (-1) + (-1) = -3, we see that Co must have a +3 charge in order to balance out the overall charge to ZERO. Hope this helps

CenCen
Posts: 29
Joined: Fri Sep 25, 2015 3:00 am

### Re: Determining Oxidation Numbers

So the oxidation number is the number we would put in parentheses like for example: tetracyanonickelate (II) ?

What would be the coordination number?

Isabella Shahmirza 2H
Posts: 30
Joined: Fri Sep 25, 2015 3:00 am

### Re: Determining Oxidation Numbers

Yes, the oxidation number for the transition metal is what you put in parenthesis. The coordination number is the number of bonds (or ligands) attached to the central atom. So in your example, the coordination number is four because there are four ligands (four CN-) attached to the central metal atom.