Properties of ionic compounds Transitional Reasoning Download PDF

Questions

1. 1.

   A student investigates the physical properties of a white crystalline solid to determine its bonding type. When struck with a small hammer, the crystal fractures cleanly along flat planes instead of deforming or flattening. Furthermore, an electrical continuity tester reveals no current through the solid sample at room temperature, but a high current is measured once the compound is melted into a liquid at 801 °C. Which deduction correctly accounts for both the mechanical response and the change in electrical conductivity of this solid?

   • A) The material consists of discrete molecules held by directional covalent bonds, which break easily under impact and release free electrons upon melting.
   • B) The impact disrupts a sea of delocalized valence electrons between metal cations, while thermal energy promotes these electrons to conduct electricity in the liquid state.
   • C) Mechanical stress forces ions of like charge into alignment causing repulsive cleavage, while melting overcomes the rigid lattice to permit ions to migrate freely as mobile charge carriers.
   • D) Weak intermolecular dispersion forces between neutral formula units collapse under stress, while thermal decomposition into isolated atoms enables molten electrical conduction.