Roman Numeral

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Adrienne_4F
Posts: 64
Joined: Fri Sep 28, 2018 12:27 am

Roman Numeral

Postby Adrienne_4F » Sat Dec 01, 2018 1:00 pm

Some of the names of molecules have roman numerals. How do we know which ones have roman numerals and what the roman numerals are?

Rachana Jayaraman 1H
Posts: 61
Joined: Fri Sep 28, 2018 12:26 am

Re: Roman Numeral

Postby Rachana Jayaraman 1H » Sat Dec 01, 2018 1:03 pm

The Roman numerals represent the oxidation number of the central metal atom/ion. The oxidation number of the metal atom and the oxidation numbers of the other ligands should add up to the overall charge on the coordination compound/ion.

amogha_koka3I
Posts: 62
Joined: Fri Sep 28, 2018 12:24 am

Re: Roman Numeral

Postby amogha_koka3I » Sat Dec 01, 2018 10:09 pm

An example is [Fe(CN)₆]4−. The oxidation state of the compound is 4- and the number for CN is -1 for 6 molecules so it is -6. You then subtract -6 from -4 to get the +2 oxidation number for Fe.

yuetao4k
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Joined: Fri Sep 28, 2018 12:27 am
Been upvoted: 1 time

Re: Roman Numeral

Postby yuetao4k » Sun Dec 02, 2018 11:36 pm

The roman numerals correlate with the transition metal's oxidation number. Ag, Fe, Cu, and Pb are some examples of elements that need a roman numeral when naming them.

Nawaphan Watanasirisuk 3B
Posts: 58
Joined: Tue Nov 28, 2017 3:03 am

Re: Roman Numeral

Postby Nawaphan Watanasirisuk 3B » Mon Dec 03, 2018 2:46 pm

Is it possible to ever have a negative oxidation number? If so how would that be reflected in the name because there is no +/- sign in the brackets

Nancy Hu - 4E
Posts: 30
Joined: Fri Sep 28, 2018 12:28 am

Re: Roman Numeral

Postby Nancy Hu - 4E » Mon Dec 03, 2018 3:51 pm

Nawaphan Watanasirisuk 3B wrote:Is it possible to ever have a negative oxidation number? If so how would that be reflected in the name because there is no +/- sign in the brackets

Yes it is possible to have a negative oxidation number. To show that it is an anion, you would add -ate at the end of the central atom's name, and its Latin name will be used if it has one.


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