Roman numerals

[Marty Hockey]

For naming compounds, how am I supposed to know which roman numeral to use for the metal atom/ion?

[Vincent Leong 2B]

You determine the charge of the polyatomic ions within the coordination sphere and compare it to the charge of the overall coordination compound to find the charge of the transition metal. For example, [Fe(CN)6]^4-, we know CN has a -1 charge. So, 6(-1) + x = -4, solve for x (x being the charge of the transition metal).

[claudia_1h]

You know this because you know the overall charge of the compound you are naming. For example, say you are naming [Co(NH3)6]3+. You know there is an overall plus 3 charge. You have 6 neutral ammonias and therefore that one cobalt must get all of the charge. Therefore, the name of this compound would be hexaaminecobalt (III) ion.

[Jielena_Bragasin2G]

The Roman numeral is the charge of the metal ion. You can find this number by finding the charge of the ligand, multiplying this charge by the number of ligands, and subtracting this number from the overall charge.

for example: [Fe(CN)6]4-
The overall charge is 4- and there are 6 CN. The formal charge of CN is -1 so multiply that by 6: -6. Then subtract -6 from -4 to get the charge of Fe, which will be your Roman numerals: 2.

The name of the compound is hexacyanoferrate (II) ion

I hope this helps!

[Astrid Lunde 1I]

The roman numeral tells us the charge on the metal ion.

[Leyna Dang 2H]

You can determine the roman numeral by finding the charge of the transition metal. If the charge is not given, you can calculate the charges of each ligand and subtracting it from the overall charge.

[TimVintsDis4L]

The roman numeral is simply the oxidation number of the central atom that makes the chemical compound neutral