Crystal lattices Transitional Reasoning Download PDF

Questions

1. 1.

   An engineer investigates the structural behavior of an ionic crystal lattice subjected to a sudden mechanical shear stress and evaluates its thermal stability relative to an analog compound. When mechanical stress displaces one layer of ions relative to an adjacent layer by a single ionic radius, the crystal fractures cleanly along a smooth plane rather than undergoing plastic deformation. Furthermore, comparing two isostructural ionic lattices with nearly identical interionic distances reveals that doubling the magnitude of the ionic charges quadruples the attractive electrostatic forces holding the lattice together. Based on these observations and the principles of ionic crystal lattices, which statement correctly explains these phenomena?

   • A) Plastic deformation is prevented because delocalized valence electrons immediately absorb the kinetic energy and pull the displaced layers apart.
   • B) Doubling ionic charges quadruples lattice stability because coordination numbers double to accommodate higher electrostatic field densities.
   • C) Mechanical fracture occurs because displacing ion layers brings ions of like charge into direct alignment causing intense electrostatic repulsion, while lattice energy scales with the product of ion charges.
   • D) Cleavage occurs because covalent directional bonds between alternating ions are permanently snapped, whereas thermal stability depends strictly on the total volume of the unit cell.