Sapling Homework W9 Problem#1

[Megan Sparrow 1A]

Hello! I was unsure of how to approach the first problem. If you have any insight, that would be greatly appreciated.

[Kiran Singh 3A]

Dr. Lavelle describes how to name coordination compounds in today's lecture. Basically, the format is greek prefix- ligand names in alphabetical order- TM cation name (Roman numeral)- anion name- greek prefix- hydrate. (greek prefix- ligand names in alphabetical order- TM cation name (Roman numeral)) is what is inside the brackets and (anion name- greek prefix- hydrate) is what is outside of the brackets. If there is nothing outside of the brackets, then do not include (anion name- greek prefix- hydrate). Hope this makes sense.

[Kareena Patel 1G]

First, you start with the ammonium (because we name in alphabetically order for the ligands), so there are 4 ammonium so it would be tetraammine. Then, you name the chloride which is dichlodide. However, be sure to drop the -ide and replace it for an -o since it is in the coordination sphere (so it is dichloro). Then, name the cobalt with the roman numeral. To do this, you have to find the oxidation number of Co. The oxidation number of NH3 is 0 since it is neutral and the charge for each chlorine is -1 for a total of -2 for the dichloride. Since the whole sphere has a +1 charge, cobalt has a +3 charge, making the name tetraammine dichlorocobalt (III). Finally, you add the molecule that is outside the sphere, and then you'd have your name for the compound.

[Frankie Mele 3J]

A good place to start with this problem is first determining how many ligands are connected to the central atom. Once you determine this, you can choose whether to start with the prefix di- tri- tetra- (etc.).

[Ria Nawathe 1C]

Hi! I had trouble with this one too, but the book has a helpful list of rules in Focus 9C.1 for naming coordination compounds/complexes.

First, everything enclosed by the brackets is part of the complex ion. The complex ion has an overall charge of +1, as Cl is -1 and the whole coordination compound is neutral. The central metal atom for the complex ion is Co. Looking at the ligands, NH3 is neutral and the 2 Cls each have a -1 charge; x + 2(-1) = +1 (which is the overall charge of the complex ion) so the oxidation state of Co is +3. To name the complex ion, name the ligands first in alphabetical order using their ligand names (discounting the prefixes in alphabetization) and then name the metal atom with the oxidation state in parentheses. For anionic ligands (like Cl), change the "ide" ending to "o" (chloride --> chloro). Therefore, the complex ion is tetraamminedichlorocobalt(III), and the whole coordination compound is tetraamminedichlorocobalt(III) chloride.

Hope this helps!

[Maddie Turk Disc 2J]

How do we find that the oxidation state is 3?