Why is it necessary to call the molecular compound NBr3 nitrogen tribromide while its not necessary (and therefore incorrect) to call the ionic compound GaF3 gallium triflouride?
The Correct Answer and Explanation is:
It is necessary to call the molecular compound NBr₃ nitrogen tribromide but incorrect to call the ionic compound GaF₃ gallium trifluoride because the rules for naming covalent (molecular) and ionic compounds are different. In molecular compounds, which are formed between two nonmetals, prefixes are used to indicate the number of atoms of each element. In ionic compounds, which are formed between metals and nonmetals, these prefixes are not used.
In nitrogen tribromide (NBr₃), both nitrogen and bromine are nonmetals. This means it is a molecular compound. To clearly communicate the number of each atom in the molecule, prefixes are applied. “Tri-” indicates that there are three bromine atoms. If you only said “nitrogen bromide,” it would not specify the actual formula since nitrogen and bromine can form more than one compound with different ratios. Therefore, the prefix is required to give the complete chemical name.
On the other hand, gallium fluoride (GaF₃) is an ionic compound, composed of a metal (gallium) and a nonmetal (fluorine). In ionic compounds, the ratio of ions is determined by the charges of the ions involved. Gallium typically forms a +3 ion, and fluoride forms a -1 ion. To balance the charges, three fluoride ions are needed for every gallium ion, giving the formula GaF₃. Since the charge of gallium is understood from its common oxidation state, and because ionic compounds do not use prefixes to indicate the number of anions or cations, it would be incorrect to call this compound “gallium trifluoride.” Doing so would imply a covalent character that the compound does not have.
In summary, prefixes are only used for molecular compounds between nonmetals to clarify composition, while ionic compounds rely on the charge-based balancing of ions and do not require or use prefixes.
