Posted by jim on Wednesday, August 17, 2011 at 8:04am.
a compound has as its fundamental unit (that cannot be subdivided without changing chemical characterists)a molecule. For instance, C6H12O5 is the formula for the molecule of sugar. If many of these molecules are grouped together, we call that grouping a chemical compound. In history, there were atoms proposed as the fundamental unit of elements, and compound atoms were the fundamental elements of chemical compounds. Over the past 150 years, we have altered the definitions slightly.
The naming system inserts into a chemical name its valence state, if it is multivalent element.
For instance CuO is no longer cupric oxide, we name it Copper(II) oxide. Many folks still hang on to the -ic; -ous, hypo -ous latin suffics/prefixes.
Cu2O is Copper(I) oxide, no longer Cuprous oxide.
Ferric becomes Iron(III)
Ferrous becomes Iron (II)
Where this new system is of great advantage, is in metals which have more than two valences. We now can easily name compounds with
Manganese(I)
Manganese(II)
Manganese(III) and so on thru Manganese(VII)
Now why Roman Numerals? Why not Arabic Numerals. That is a really good question. The answer lies in history and how history leads to symbols, and our ties to the Romans, I guess.
Bob,
I believe roman numerals were chosen to avoid potential confusion with Arabic Numerals which are used to indicate composition. As you say they have been used historically to indicate oxidation state.
Related Questions
Honors Chemistry - Can someone please explain to me how to use the stock naming ...
Math: Roman Numerals( story problem ) - i know roman numerals, but i forget all ...
Chemistry - How do you know when to put roman numerals into formulas of binary ...
science grade 10 chemistry - do you know any website that helps explain how the ...
roman numerals - are roman numerals in numeric order also in alphabetical order...
roman numerals - 1}The Romen numeral M represents: a.50 b.100 c.500 d.1000 2}The...
chemistry - what is the difference between ionic and molecular/covalent ...
math - in roman numerals, letters represent numbers. for example, I=1,V=5,X=10,L...
chemistry - onic compounds have names that... (choose all that apply) might ...
Roman Numerals - what is the roman numeral for 4??
For Further Reading
