National League for Nursing (NLN) Science Practice Exam

What type of bond is created when bromine and magnesium react to form MgBr2?

1. polar covalent

2. metallic

3. ionic

4. nonpolar covalent

The correct answer is: ionic

When bromine and magnesium react to form MgBr2, an ionic bond is created. This occurs due to the significant difference in electronegativity between magnesium and bromine. Magnesium, a metal, has a tendency to lose electrons, while bromine, a nonmetal, tends to gain electrons. In this reaction, magnesium donates two electrons to two bromine atoms. This transfer of electrons leads to the formation of positively charged magnesium ions (Mg²⁺) and negatively charged bromide ions (Br⁻). The strong electrostatic attraction between these oppositely charged ions is what constitutes an ionic bond. The characteristics of ionic compounds include their crystalline structure and high melting and boiling points, which arise from the strong forces holding the ions together. This bond is distinctly different from polar covalent or nonpolar covalent bonds, which involve sharing of electrons, and metallic bonds, which involve a sea of delocalized electrons among metal ions. Hence, the reaction results in the formation of ionic compounds such as magnesium bromide.