Question

on the basis of electronegativity differences between atoms, which of the following scientific claims is the most accurate regarding the bonding in mg(no₃)₂(s)?
a there is polar covalent bonding between mg atoms and n atoms.

b there is polar covalent bonding between mg atoms and o atoms.

c there is ionic bonding between n³⁺ ions and o²⁻ ions.

d there is ionic bonding between mg²⁺ ions and no₃⁻ ions.

Explanation:

1. First, analyze the compound $\ce{Mg(NO_{3})_{2}}$. Magnesium nitrate is an ionic compound. Magnesium ($\ce{Mg}$) is a metal, and in this compound, it forms $\ce{Mg^{2+}}$ ions. The nitrate group is $\ce{NO_{3}^{-}}$, a polyatomic ion.

• For option A: $\ce{Mg}$ is a metal and $\ce{N}$ is in the polyatomic ion. $\ce{Mg}$ and $\ce{N}$ do not form a bond directly in the way described; instead, $\ce{Mg}$ forms ions with the nitrate polyatomic ions. So A is incorrect.
• For option B: Similarly, $\ce{Mg}$ (a metal) and $\ce{O}$ (in the nitrate group) do not have a direct polar covalent bond. $\ce{Mg}$ forms ionic bonds with the nitrate ions. So B is incorrect.
• For option C: The ions present in $\ce{Mg(NO_{3})_{2}}$ are $\ce{Mg^{2+}}$ and $\ce{NO_{3}^{-}}$, not $\ce{N^{3 - }}$ and $\ce{O^{2 - }}$ in the way this option suggests. The nitrate ion is a polyatomic ion, and the bonding within the nitrate ion is covalent, but the bond between $\ce{Mg^{2+}}$ and $\ce{NO_{3}^{-}}$ is ionic. So C is incorrect.
• For option D: In $\ce{Mg(NO_{3})_{2}}$, magnesium exists as $\ce{Mg^{2+}}$ cations and nitrate exists as $\ce{NO_{3}^{-}}$ anions. The electrostatic attraction between these oppositely charged ions ( $\ce{Mg^{2+}}$ and $\ce{NO_{3}^{-}}$) is ionic bonding. This accurately describes the bonding in magnesium nitrate.

Answer:

D. There is ionic bonding between $\ce{Mg^{2+}}$ ions and $\ce{NO^{-}_{3}}$ ions