Which of the following compounds contains both ionic and covalent bonds? — Bonding Chemistry Question

STEPS:

1. Understand the definitions of ionic and covalent bonds:
* Ionic bonds are electrostatic attractions that occur between oppositely charged ions (typically a metal cation and a nonmetal anion, or involving polyatomic ions).
* Covalent bonds are formed when nonmetal atoms share valence electrons with each other.
2. Identify the structural prerequisite for having both bond types: For a single compound to contain both ionic and covalent bonds, it must be an ionic compound that contains at least one polyatomic ion. Polyatomic ions are groups of atoms held together by covalent bonds that collectively carry a net positive or negative charge.
3. Analyze the bonding in ammonium chloride ($\text{NH}_4\text{Cl}$):
* Ammonium chloride is an ionic compound composed of the polyatomic ammonium cation ($\text{NH}_4^+$) and the monatomic chloride anion ($\text{Cl}^-$).
* The electrostatic attraction holding the $\text{NH}_4^+$ cation and the $\text{Cl}^-$ anion together in a crystal lattice is an ionic bond.
* Within the polyatomic $\text{NH}_4^+$ cation, the central nitrogen atom is bonded to four hydrogen atoms through shared electron pairs, which are covalent bonds.
* Because both bond types are present in this single substance, $\text{NH}_4\text{Cl}$ contains both ionic and covalent bonds, making Option E the correct answer.

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WHY_OTHERS_WRONG:

• A is incorrect: Sulfur trioxide ($\text{SO}_3$) is a molecular compound made up entirely of nonmetal sulfur and oxygen atoms sharing electrons. It contains only covalent bonds.
• B is incorrect: Ethanol ($\text{C}_2\text{H}_5\text{OH}$) is an organic molecular compound composed of carbon, hydrogen, and oxygen atoms sharing electrons. It contains only covalent bonds.
• C is incorrect: Magnesium fluoride ($\text{MgF}_2$) is a binary ionic compound consisting of monatomic magnesium cations ($\text{Mg}^{2+}$) and monatomic fluoride anions ($\text{F}^-$). It contains only ionic bonds.
• D is incorrect: Hydrogen sulfide ($\text{H}_2\text{S}$) is a molecular compound consisting of hydrogen and sulfur atoms sharing electrons. It contains only covalent bonds.