What is the molecular geometry (shape) of the ammonium chloride molecule?
The Correct Answer and Explanation is :
Molecular Geometry (Shape) of Ammonium Chloride:
The molecular geometry of the ammonium ion (NH₄⁺) in ammonium chloride (NH₄Cl) is tetrahedral.
Explanation
Ammonium chloride (NH₄Cl) is an ionic compound, not a covalent molecule. It consists of two ions: the ammonium ion (NH₄⁺) and the chloride ion (Cl⁻). Since it is composed of ions, NH₄Cl does not have a single molecular geometry as a whole unit. Instead, we analyze the geometry of the polyatomic ion NH₄⁺, which is the part with defined molecular geometry.
Structure of NH₄⁺:
The ammonium ion is derived from ammonia (NH₃) by the addition of a proton (H⁺). This changes the nitrogen atom from having a lone pair (in NH₃) to having four bonding pairs (in NH₄⁺), since it forms four N–H covalent bonds. The central atom is nitrogen, and it is surrounded by four hydrogen atoms.
To predict the shape, we use the Valence Shell Electron Pair Repulsion (VSEPR) theory, which states that electron groups around a central atom will arrange themselves to minimize repulsion.
- In NH₄⁺, nitrogen has 4 bonding pairs and 0 lone pairs.
- According to VSEPR theory, this corresponds to an AX₄ type geometry, which is tetrahedral.
- The bond angles in a perfect tetrahedron are approximately 109.5°.
Chloride Ion (Cl⁻):
The chloride ion (Cl⁻) is a monatomic ion with a full octet (8 valence electrons). It does not form covalent bonds in NH₄Cl but instead interacts ionically with the positively charged NH₄⁺ ion.
Conclusion:
While ammonium chloride (NH₄Cl) is an ionic compound, the molecular geometry applies to the NH₄⁺ ion, which is tetrahedral in shape. The Cl⁻ ion simply associates electrostatically and does not alter the geometry of NH₄⁺.
