enthalpy

Definition of first ionization energy

The energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous +1 ions

Enthalpy of atomization

The enthalpy change required to break a covalent bond with all species in the gaseous state

First electron affinity

The energy released when one mole of electrons is added to one mole of gaseous atoms to form one mole of 1- ions

Enthalpy of formation

The Enthalpy change for the formation of one mole of a substance in its standard state from its constituent elements under standard conditions.

Lattice Enthalpy of formation

The energy released when one mole of an ionic solid compound in its standard state is formed from its constituent gaseous ions.

Born-haber cycle

Is an Enthalpy/hess cycle composed of all the Enthalpy changes involved in the formation of 1 mole of ionic compound from its constituent elements in their standard states.

Explain the difference between the Theoretical and experimental values of lattice Enthalpy

Theoretical values assume that the compound is purely ionic

Experimental values are usually higher than the theoretical value, because the lattice Enthalpy is greater due to polarization.

So there is a large discrepancy between them

Explain why the experimental and theoretical values of lattice energy are significantly different between calcium iodide. When theoretical=-1905 kJMol-1 experimental=-2074 kJMol-1

Because calcium iodide has polarization in the ionic bonds causing it to exhibit covalent characteristics. Causing the binds to deform and become polarised. Therefore has a greater lattice Enthalpy. The theoretical value assumes Calcium Iodide is 100% ionic compound