5.2.1 - Lattice Enthalpy Flashcards
What is lattice enthalpy?
The formation of 1 mole of ionic lattice from gaseous ions.
What are the standard conditions?
1 atm, 298K
What does lattice enthalpy indicate?
The strength of attraction of the ionic bond.
What does lattice enthalpy depend on?
Size and charge on the ion.
What does a smaller ion result in?
Higher charge density so ions pack more closely together and attract each other more strongly and so more exothermic lattice enthalpy.
What happens to size on the periodic table?
Increases down the group, decreases across a period.
How does ionic charge affect lattice enthalpy?
The higher the charge on the ion, the higher the charge density so ions attract each other more strongly and so more exothermic lattice enthalpy.
When looking at lattice enthalpy, which property takes priority?
Charge
Enthalpy of solution?
When 1 mole of a solute is completely dissolved in water.
Enthalpy of hydration?
1 mole of aqueous ions are formed from their gaseous ions.
How do ionic charge and size also affect enthalpy of solution?
The higher the charge density the stronger the attractions between ions and water molecules.
Why is 2nd ionisation energy more endothermic?
The positive ion is smaller than the element, so greater attraction from nucleus.
Why is 2nd electron affinity positive?
Energy is required to overcome repulsion from negative ion and negative electron.
