Factors effecting size of lattice enthalpy

Question 1

What is charge density?

Answer 1

Charge/volume

Question 2

What is the effect of charge density?

Answer 2

The higher the charge density, the stronger the electrostatic attraction

Question 3

What are factors effecting ionic strength/lattice enthalpy?

Answer 3

Charge on the ion, ionic radius and charge density

Question 4

What is the trend on ionic substance with the same charge?

Answer 4

The larger the ionic radius, the less the exothermic lattice enthalpy do the electrostatic attraction between ions is weaker due to charge density of ions being lower

Question 5

What is the trend with ionic substances with different charges (e.g. MgO and Na2O) ?

Answer 5

Mg²⁺ has a smaller ionic radius, Mg²⁺ is more highly charged and has a higher charge density so stronger electrostatic attraction to O²⁻

Question 6

How do the lattice enthalpy change when the radius of the negative ion increases?

Answer 6

It becomes less negative as the charge is distributed over a larger volume so attraction to positive ion dcreases

Question 7

What is the relationship between lattice enthalpy and melting point (of an ionic compound) ?

Answer 7

A compound with more negative lattice enthalpy would be expected to have a higher melting point because the ionic bonding is stronger