Question

what is the proper name for $\ce{mgbr_{2}}$?
\bigcirc magnesium bromide
\bigcirc magnesium (i) bromide
\bigcirc magnesium (ii) bromide
\bigcirc magnesium dibromide
\bigcirc monomagnesium dibromide

Explanation:

To name \( \text{MgBr}_2 \), we first identify the ions. Magnesium (\( \text{Mg} \)) is an alkaline earth metal and forms a \( +2 \) ion (Mg\(^{2+}\)) because it belongs to Group 2 of the periodic table, so it has a fixed oxidation state of \( +2 \). Bromine (\( \text{Br} \)) forms a \( -1 \) ion (Br\(^-\)). In ionic compounds, we use the name of the cation first, followed by the name of the anion. Since the cation (magnesium) has a fixed oxidation state (no need for Roman numerals), we name the anion (bromide) and do not use prefixes for the cation (as it's a simple ionic compound with a metal of fixed charge). So the name is magnesium bromide. The other options are incorrect: magnesium (I) bromide implies a \( +1 \) charge on Mg (wrong), magnesium (II) bromide is unnecessary as Mg's charge is fixed, and the prefix -based names (dibromide, monomagnesium dibromide) are not used for simple ionic compounds with metals of fixed charge.

Answer:

A. magnesium bromide