Roman numerals

[Lelija Kazlauskas 3J]

When are we supposed to use Roman numerals when naming compounds?

[sarahsalama2E]

When it is a transition metal, because the oxidation number can change. So, denoting the oxidation number through roman numerals and parentheses is necessary to denote exactly what compound you are talking about.

[Aliya Jain 2B]

For example, Ni (I) would represent the +1 oxidation number of nickel while Ni (II) represents the +2 oxidation number

[Robin Cadd 1D]

When it is common for an element to have more than one possible charge (i.e. it's common that Fe has either a charge of 2+ or 3+), Roman numerals are used. These Roman numerals help to identify the compound.

[Megan_1F]

What exactly is oxidation number?

[anjali41]

According to the textbook, an oxidation number is "the effective charge on an atom in a compound, calculated according to a set of rules (see Toolbox K.1). An increase in oxidation number corresponds to oxidation; a decrease corresponds to reduction."

[britthanul234]

The oxidation number is the effective charge on an atom in a compound. A larger oxidation number means more oxidation while a lower oxidation number means the opposite, which is reduction.