What is lattice enthalpy?

Lattice enthalpy refers to the energy change that occurs when gaseous ions combine to form a solid ionic compound. Specifically, it is often defined as the amount of energy released when one mole of an ionic solid is formed from its constituent gaseous ions under standard conditions. This process is exothermic, meaning energy is released to the surroundings.

The concept is fundamental in understanding the stability of ionic compounds; a greater lattice enthalpy indicates a more stable ionic solid because more energy is required to separate the ions back into the gaseous state. It plays a crucial role in determining the solubility and melting points of ionic compounds, as stronger lattice energies typically correspond to lower solubility in solvents.

The other options do not accurately describe lattice enthalpy. The energy change when forming a liquid from a solid describes enthalpy of fusion, while temperature fluctuation in metals relates to thermal properties, and metallurgical conductivity is unrelated to lattice enthalpy. Thus, the first choice directly describes the phenomenon of lattice enthalpy and its significance in ionic compounds.