Why do we call Ba(NO3)2 barium nitrate, but we call Fe(NO3)2 iron(II) nitrate?
Câu trả lời tốt nhất
Primarily, I’d guess it’s because barium has (apart from some rare counterexamples) one oxidation state: +2. So when you say “barium nitrate”, you know exactly what the formula should be. Iron, however, has a number of oxidation states, of which several are very common and two form nitrates: +2 and +3.
So if you say “barium nitrate,” there is no ambiguity – it’s Ba(NO3)2. If you say “iron nitrate,” it could be Fe(NO3)2 or Fe(NO3)3. So we add the bit in parentheses to let us know which oxidation state we’re interested in.
You could also use the old names for the +2 and +3 iron forms: “ferrous” and “ferric”. Then, “ferrous nitrate” means Fe(NO3)2, and there is no ambiguity.