Ionic compounds and formula units Original Scenario-Based Download PDF

Questions

1. 1.

   During an exploratory expedition inside a crystalline cavern on an uncharted moon, astrochemists analyze a luminous mineral composed exclusively of calcium ions ($\text{Ca}^{2+}$) and nitride ions ($\text{N}^{3-}$). A rookie researcher mistakenly records in the mission log that the solid deposit is composed of isolated five-atom molecules held together by weak forces. Which statement correctly resolves this error by describing the true structural nature and formula unit of the mineral?

   • A) It forms an extended three-dimensional crystal lattice of alternating ions, where the formula unit $\text{Ca}_3\text{N}_2$ denotes the lowest whole-number ratio of ions ensuring electrical neutrality rather than a discrete molecule.
   • B) It consists of distinct five-atom molecular clusters held together by covalent sharing, where the formula unit defines the physical boundaries of each isolated particle.
   • C) It forms a delocalized metallic lattice where valence electrons drift freely among neutral atoms, meaning the formula unit indicates an empirical mass percentage.
   • D) It exists as independent diatomic ion pairs held together by weak intermolecular attractions, with the formula unit indicating the average size of transient clusters.