What is the standard practice for writing the name of a binary ionic compound?

The standard practice for writing the name of a binary ionic compound involves using Roman numerals to indicate the oxidation state of the metal cation when it has more than one possible charge. This is especially important for transition metals, which can exhibit variable oxidation states. For example, in the compound FeCl2, the iron is in the +2 oxidation state and is named iron(II) chloride, while in FeCl3, the iron is in the +3 oxidation state and is referred to as iron(III) chloride. The use of Roman numerals helps to clarify which specific cation charge is present, preventing confusion in chemical nomenclature.

In contrast, changing the nonmetal's name to include "ate" is not applicable for binary ionic compounds, as that suffix typically pertains to polyatomic ions. Starting with the anion's name is incorrect because binary ionic compounds are named by starting with the cation followed by the anion. Placing "acid" at the end of the name relates to naming acids rather than binary ionic compounds, which do not incorporate "acid" in their names. This highlights the specific role of Roman numerals in providing clarity and precision in chemical names of ionic compounds.