22.3 Factors affecting lattice enthalpy

Question 1

what are the properties of ionic compounds?

Answer 1

high melting and boiling points
soluble in polar solvents
can conduct electricity when aqueous

Question 2

what is the affect of ionic size on lattice enthalpy?

Answer 2

if the ionic radius is larger, the attraction between the ions decreases

means more energy is needed to form a lattice structure hence the lattice enthalpy is less negative (so is greater)

Question 3

what is the affect of ionic charge on lattice enthalpy?

Answer 3

if there is a greater ionic charge, the attraction between the ions increases

means less energy is needed to form a lattice structure hence the lattice enthalpy becomes more negative (so is smaller)

Question 4

how does an increasing ionic charge and decreasing size affect the lattice enthalpy?

Answer 4

stronger ionic charge and a smaller ionic size means stronger attraction between ions so more negative lattice enthalpy

GOING ACROSS A PERIOD

Question 5

what is the relationship between lattice enthalpy and melting point?

Answer 5

a more negative lattice enthalpy means a higher melting point

a more negative lattice enthalpy suggests a strong attraction between ions in a lattice which means more energy would be needed to break the lattice

Question 6

what is the affect of ionic size on hydration?

Answer 6

if the ionic radius increases, the attraction between the ions and water decreases

means more energy is needed to dissolve the ions so a less negative hydration energy

Question 7

what is the affect of ionic charge on hydration?

Answer 7

if the ionic charge increases, the attraction between ions and water increases

means less energy is needed to dissolve the ions so a more negative hydration energy

Question 8

what is the relationship between hydration energy and solubility?

Answer 8

a more negative hydration energy suggests a stronger attraction between water molecules and ions so greater solubility