explain why lattice energy of NaF is less exothermic than MgF2
Answers
Answer:
greater the charges of cation & anion, higher will be the lattice energy of the corresponding salt. Again, smaller the ionic radii of cation and anion, higher will be the lattice energy. Now, in comparison between MgF2 & LiF, we deal with Mg+2, Li+ and F– (in both case) ions. Mg+2 has higher (+ve) charge than that of Li+ and ionic radius of Mg+2 is smaller than that of Li+. Hence, it is clear that MgF2 has higher lattice enthalpy than that of LiF.
Answer:
As an example, MgO is harder than NaF, which is consistent with its higher lattice energy. In addition to determining melting point and hardness, lattice energies affect the solubilities of ionic substances in water. In general, the higher the lattice energy, the less soluble a compound is in water
Radius of ions
As the size of halide increases down the group, the lattice energy decreases. This is because with the increase of size of ions, the distance between their nuclei increases. Thus the attraction between them decreases and finally the less lattice energy released during the process.