## Roman numerals

lauraxie2e
Posts: 108
Joined: Fri Aug 09, 2019 12:17 am

### Roman numerals

How do you know what Roman numeral to put after the name, when you're naming the compound? For example how do you know that [Fe(CN)6]4- is hexacyanidoferrate (II) and not hexacyanidoferrate (III)?

Brian_Ho_2B
Posts: 221
Joined: Fri Aug 09, 2019 12:16 am

### Re: Roman numerals

The sum of each oxidation number in the coordination compound should add up to the total charge of the complex, which in this case is -4. Each CN is a -1 and there's 6 of them, so those are a total of -6. To have a sum of -4, the charge of the cation must be +2.

Ryan Yee 1J
Posts: 101
Joined: Sat Aug 17, 2019 12:16 am

### Re: Roman numerals

The roman numeral refers to the oxidation state of the transition metal in question. In your example, Fe's charge is 2+, so you would use iron (II) when naming it. If its charge were to 3+, you would use iron (III).

105289321
Posts: 49
Joined: Sat Sep 07, 2019 12:15 am

### Re: Roman numerals

The numerals represent the charge of the metal ion in question

ariaterango_1A
Posts: 57
Joined: Wed Sep 18, 2019 12:15 am

### Re: Roman numerals

The roman numerials represent the oxidation number of the transition metal.

Caroline Zepecki
Posts: 101
Joined: Fri Aug 09, 2019 12:16 am

### Re: Roman numerals

You determine roman numeral by finding the oxidation number of the metal. You determine the charge on the ligand, and if the coordination compound is an ion, then you can find the oxidation number by determining what number will make all charges true.

705198479
Posts: 55
Joined: Wed Sep 18, 2019 12:20 am

### Re: Roman numerals

The Roman numeral must have the same value as the charge of the ion?