Which of the following represents the kind of bonding present in ammonium chloride?

Analysis

To determine the type of bonding in ammonium chloride ($NH_4Cl$), we need to look at the structure of the compound and how its constituent parts are held together.

Concept Explanation

Ammonium chloride is an ionic salt composed of two distinct ions:

1. The Ammonium Ion ($NH_4^+$): This is a polyatomic cation. Within this ion, the nitrogen atom is bonded to four hydrogen atoms. These bonds are covalent (sharing of electrons). Furthermore, one of these bonds is specifically a dative (coordinate) covalent bond, where the nitrogen atom donates its lone pair of electrons to a hydrogen ion ($H^+$).
2. The Chloride Ion ($Cl^-$): This is a simple anion.

Because the compound consists of a positively charged ammonium ion ($NH_4^+$) and a negatively charged chloride ion ($Cl^-$), there is a strong electrostatic force of attraction between them. This electrostatic attraction is the definition of ionic bonding.

Step-by-Step Solution

1. Identify the internal structure: Inside the $NH_4^+$ ion, the atoms are held together by covalent bonds (including a dative bond).
2. Identify the external structure: The $NH_4^+$ cation and the $Cl^-$ anion are held together by electrostatic forces, which is an ionic bond.
3. Combine the findings: Since the compound contains both covalent bonds (within the ammonium ion) and ionic bonds (between the ammonium and chloride ions), the bonding is both ionic and covalent.

Conclusion

While ammonium chloride does contain dative covalent bonds, the question asks for the kind of bonding present in the compound as a whole. Because it is an ionic salt containing a polyatomic ion with covalent internal bonds, it is categorized as having both ionic and covalent bonding.

Exam Tip

Whenever you see a salt containing a polyatomic ion (like $NH_4^+$, $SO_4^{2-}$, $NO_3^-$, or $CO_3^{2-}$), remember that the bond between the metal/cation and the polyatomic ion is ionic, but the bonds inside the polyatomic ion are always covalent.